I have been that lady.
Now, looking back after 15 years I wish someone had helped me not to 'wallow'. That's not the right word but you get my meaning?
The idea to schedule your grieving time is good.
It's a terrible period, and she may have lost a lot of her interests and mojo during his long illness.
I would suggest, if you want to stay friends, suggest outings where there other topics will naturally arise.
Let her sometimes talk about it. The first and second years are horrible; especially the second year, in my experience, is even worse.
Or encourage her to go to her GP as she may be grieving or she may have become depressed.
Suggest local support centers that do activities?
It's difficult for both of you. She needs help to live again when, sometimes, she won't know how to, or admitting she wants to can feel disloyal.
So many friends disappear after bereavement.
I think you have to honestly ask yourself if you are, underneath it all, good enough friends that you really want to be there for the long-haul.