I'm currently dealing with breast cancer (mastectomy is done, waiting to find out about chemo), and while I would loooove a pale pink quilt - because that is one of my favorite colors - I would really prefer not to have one that screams "breast cancer" every time I saw it. Something in her favorite colors, or something that goes with the decor of her home, would be preferable, in my opinion. As far as batting, I'd go with light or medium, but again, that's just my preference; I'm not usually a fan of pouffy quilts. Size, maybe lap size or something large enough to cover her entirely, neck to feet. I know when I got home from the hospital, I was freezing for the first couple of weeks and always wanted something to keep me warm (of course, it was also January and the middle of that polar vortex mess, but even if she does treatment in the summer, there's always air conditioning to contend with). Anyway, I think it's really sweet of your son to suggest it!