Watching a loved one go thru all they can go thru is cruel ... but hopefully the patient has very limited ability to understand what's going on.
I had a grandmother, just over 20-years ago who died while in one of the more archaic homes for alzheimers. She was about 4'-11" and spitting mad with or during much of her last year in that home.
My mother has been in an assisted living home for dementia and parkinsons for 13-months now ... after living at home for 15-months with a 24/7 caregiver. I have watched her fade, especially the past few months - not violent yet, but that could happen .... but I see fear. And I think it's fear of feeling alone. She just turned 96 last month.
I can't imagine anyone in the health industry would just let her die ... but does she or did she have any kind of an assignment for health power of attorney? If she has a "do not recusitate (spell?)" .... it might be the best for her pain management ... and provide the least amount of guilt for any family member.
Best wishes to you and yours.
Rob and Gizzy