Please tell me why my mother-in-law is hanging on so long?

My mother-in-law lives with me and my husband. She is 86 years old. Over the last few months she seemed to deteriorate. She has many illness, but her congestive heart failure is really bad. When she got out of the hospital the last time we ask for hospice. She was eating less and less. Some days not eating or drinking at all. When hospice came in we didnt try to feed her or give her water. We would swab her mouth with cold water. She suffered a massive stroke, but still is living. It has been four days now. She cant talk or get out of bed anymore. She was totally unresponsive. Then all of a sudden she seemed to make a comeback sort of. She opens one eye, moves her left arm and and very lightly squeezes our hand with hers. Why is this process taking so long. She is now crying when we go into the room and seems to be wanting to talk but cant. This is very disturbing to my husband and his sister to the point that they are second guessing their decision to no feed her. I went in this am and she turned her head towards me and was moving her mouth and crying. I was stead fast on the fact that this was the right thing to do, but now I am faulting also. Why was she so bad and now seems to be getting better? Thank you for your help. Donna in Florida