I agree with the idea of a comfort quilt. Personally I never want a memory quilt. I have a mentally ill father and don't have a lot of happy memories and even a good memory can dredge up a bad one. I do not live in my past. That is why I don't go to psychiatrists. They just kept me stirred up remembering all the crap I had to endure.
I would suggest that after quite a bit of time has passed I would bring up the idea of a memory quilt with her. Not letting her know it would be for her. Something like "a lot of the quilters on my quilt board are making memory quilts for people that have lost someone dear to them. I have mixed feelings about them. What do you think? " How she answers this would give you a key into how she feels about such a thing.
Hope this helps. And HUGS for you.