My grandmother sleeps for 20 plus hours, when she wakes up to eat, she will eat nothing but sweets...should I stop this?

I am the primary caregiver for my 90 year old grandmother. She has now started sleeping 20 plus hours without waking. When she is awake, she doesn't drink much water, she will have 2 toaster strudel for breakfast, a huge bowl of ice cream at 10:00, cookies for lunch, more ice cream after her nap and then whatever I fix for dinner...she is weak and irritable. How can I get her to eat other things that are more healthy