Do I have to go?

Ninathenana's idea is really good!

I went to DD's and DIL's hen nights
DD's future MIL was invited too and MIL took a couple of her own friends too! I get on well with DD's friends but went home after the meal and left the younger ones to it.
DIL's was at a local restaurant and her mum was there, of course, and another lady our age who is a friend of DIL through work.

Both were great fun, but not that expensive(why are some of them so extravagant these days?).

Another shout for nina here.
My daughter had a do in our nearest city, 12 miles away. It started about 2, I was invited with two of my closest friends who have been involved since daughter was a baby. Mil was also invited. We four stayed until about 6 when the gang of, by them slightly squiffy, young women went off for a meal and onwards to party on. We thanked them, lots of hugs and cuddles all round and off we went home.
It's so kind to invite us but honestly, playing out from 2 - 2 am isn't for me (any more)

Another here who agrees with nina. It wouldn't really be my thing either. I was prevented from going to my DD's meal in London by having a broken ankle, so I ordered some flowers to be delivered to her table. The drinks offer is a good idea and just be honest with your son about your reservations. The drinks gesture, I'm sure, will be gracefully accepted and save you a lot of expense.

I think Nina gives good advice......
I was invited to my d-i-l's hen-do (now an ex-d-i-l) it was in London, theatre, a show, an overnight and lots of fizz..... My DD and I shared a room (made a small saving there) but the rest just had to be swallowed up with a big smile. To be fair we had a great time (even though she is now an ex) and I still have very fond memories of the event

I was invited to my DIL's hen do and accepted, although I didn't go to any of DDs' because they involved travelling abroad for at least 3 days. I knew I wouldn't have been able to hack that! And I think I was expected to refuse!!

DIL had a picnic on Hampstead Heath with her friends, mum, auntie, my DD3 and her baby who wore an 'honerary chick' tee shirt. It was lovely. Later we went to a Bollywood dance class (DIL is half Indian) which was the best fun. After that, her mum, auntie and I withdrew and let the young ones party on at the local pub. Everyone enjoyed the day, it didn't cost a lot and DIL was happy.

Honestly, if you don't want to go, just say it isn't your sort of thing and, as others have suggested, donate some money for a round of drinks.

Hmm. Difficult. I did go to my DD's do with some trepidation and it turned out quite well but I don't think you should feel obliged to go as it sounds quite costly. As others have suggested, I'd give her the money for a round of drinks and opt out, especially as it doesn't sound like you get on particularly well with the other oldies.

DD1 had 2 hen nights, one was at a local restaurant for the oldies and then the youngsters did the wilder one. Kept everyone happy and didn't break the bank.

I did what nina said when I was asked and it was Ok no-one minded.

What nina said. I was invited to DD2'S hen do on the understanding that I refused AND told her future mum in law that I wasn't going in the hope she would take the hint.

Her mum is going. And an aunt. We don't really have much in common so I suppose I'm also wary of being stuck with them the whole night. Though that's not the main reason.
My son would 100% go straight to his fiancee unfortunately - he's very much into the no secrets between us thing. Thanks nina - you've worded that very nicely. That might work. Am surprised and also quite touched she asked. I suppose I could afford it at a stretch but it would be a stretch and I'm not sure it'd mean that much to her to make it worthwhile. Did you go to your dils' dos?

Do you know if her mum or anyone else of similar age is going? If they aren't you can just say you'll leave it to the youngsters and as Nina says offer to buy a round. Could be she feels obliged to ask you?

And Jen

Good advice Nina

Can't you speak discretely to your son and explain that although you are honoured that his finance invited you, it's a bit too expensive for your budget.say that you would like to decline but don't want to make the bride feel awkward so will say that you can't make it. Surely he would understand?

Thank her profusely and maybe give her some cash "to have one on me" and tell her that your sure she and her mates will have a great time and an even better one if she doesn't have to keep checking if future MiL is ok.