DIL rude to me

I wouldn't say anything at a time when your daughter in law has just lost her mum.
That would absolutely end up in tears.
Who knows, she may warm towards you a little at this time. (Or not, as the case may be)

Exactly what MissAdventure said.

I would agree with MissA, perhaps not the time to say how you feel. Just be there to support your DIL and son.

Your dil has obviously agreed that you are welcome at her house to help them cope at this was time so I think I'd give her a break and just go and support them .. All of them and not sit and wait for nastiness. If she is a little short then ignore it and try to comfort her .

My thoughts are the same as Nanabilly. Go, play it by ear, and do whatever she will let you to help.

My advice would be not to say anything so as to preserve your relationship with your son. He will support her in any instances of falling outs.
In my case, which I’ve posted about before, I’ve been hurt so many times by the attitude of my DIL, but have resigned myself to the fact that she simply doesn’t like me, has zero interest in our side of the family. When I visit them overseas once or twice a year I am polite, show interest in her and her job etc, then get on withplaying with my lovely grandchildren. It has taken me 12 years to get the point of resignation and acceptance that there will never be any sort of relationship between us.
I did think several times that I should “ have it out with her” but decided against it and didn't rock the boat. I’m glad I didn’t.

I can't advise anything different to what has already been said. Just to bear in mind that this is a very difficult time for your DiL, who, if she was close to her Mum, will be feeling the loss deeply and will need love and support. Also, grief affects people differently, and if she seems even more distant, this may be why. Tread sensitively.

Agree absolutely with MissA, go with an open mind, now is not the time to speak your mind.

I suggest being super nice to her at this tough time. Most of us will remember the death of our mothers. Not that anyone can replace a good mum but you are now an older female ear in "her" family.
Give HER needs your full attention and I think it may pay off. Always check with her that you are doing what she wants. Check with the children "is this the way mummy does it?" and I think it'll be fine.

Show your most compassionate side, be gentle, be kind, be helpful, bite your tongue if necessary and make your ds proud.

Be the grown-up. Be nice. Turn the other cheek and ignore it the rudeness and passive aggressive stuff. If you challenge her you have a lot to lose, as your son will side with his wife if you make him choose - then you’ll have nothing. It’s happened to TWO friends of mine and now they don’t get to see their grandchildren. Sometimes you just have to grit your teeth and smile and give the love, even if you don’t feel like you’re getting it back.

Say nothing, turn the other cheek, be kind and helpful but not interfering. DiL will be very upset and grieving. Now is the chance to make relationships with other members of her family and their friends. Greet as many as possible. Say some nice words about DiL's mother and how sorry you are etc. Later you may benefit as there may be someone in her family who speaks positively about you to her. However your actions have to be sincere, not over the top, otherwise this is manipulation.

After the funeral you can write to your son and MiL with a card and repeat some of the positive things said about her mother by the guests.

What a sad time for DIL the loss of her mother and a new baby be supportive turn the other cheek and choose your words carefully

I agree with the other comments. My husband’s DiL hates us and, for no reason, has stopped us from seeing the GC many times, sometimes for years at at time. We weren’t told that they’d moved away or that she was pregnant. At the moment we’ve not seen them for four years and we are blocked on Facebook. Tread very carefully. It may feel awful, but anything is better than being cut off totally.

I can add nothing to the wonderful advice given above. She will be grieving for her DM , ignore any unkind remarks & enjoy you DGC

The fact, the very fact, that you were considering raising this during a visit following the loss of your DIL’s mother speaks volumes to me.

I wooldnjazard a guess that your DIL behaves like this towards you because of your behaviour towards her.

Give her a hug she must be devastated at the moment and she needs all your support as others have said bite your tongue and be gentle.
Offer to be available when if she needs help in the near future.

she is always cool towards me and often rude but during the year she has been married to my son

Could this be put down to the fact that your DIL already knew her was ill/hadn't long to live? If that were the case, then her emotions will have been all over the place and possibly exacerbated by the stress of the wedding.

You don't say how long you've known your DIL, just that she married your DS a year ago. If you've known her for longer, was she always cool towards you or has she changed since the wedding?

Either way, now is not the time to do anything other than show her compassion and be as supportive as you can.

Try to wipe the memory of her unkindness to you and just see her as a girl who has lost her Mum. So much good advice here. Be as kind as you can possibly be and just hope it will pay off in her future relationship with you.

Great advice, eventually she will see you for the lovely person you clearly are. x

You may find your relationship changes now she's lost her mum. Think longterm, be quietly supportive of them both for the next year and then assess whether it's different from how it has been for the last year.

I think if you confront your DIL particularly at this time, you will compound how she seems to feel about you. Swallow hard and be as amiable as is appropriate, it could be a good step towards building bridges

What everyone else has said, give her support and be kind, she must be very upset at the moment, losing her mum especially when she has just had a baby.
Presumably you will be looking after the baby while they go to the funeral and not going yourself; if you have some nice words to say to her about her mother that would be kind too.

I agree with the very wise advice given above. Whatever you are feeling, your DiL will be feeling very much worse at the moment.
Be the grown up, show love and compassion.
What goes around comes around, maybe not straight away but eventually.