I've been in your shoes too many times.
If she's willing, go ahead. If not, don't.
With my Dad the best portrait of him was taken during his time in hospice. As he deteriorated I put away the camera. To be honest, I wouldn't want any pictures of him in that condition. The memories in my head hurt enough.
Do what's right for her, you, and your family. You know what's right; we don't!