I can relate very well to your situation. My aunt battled with leukemia for many years and near the end she was in and out of the hospital, sometimes staying for over a month. Finally, she was allowed to go home after nearly 2 months in the hospital, and a home nurse would help with cares, etc. She ended up just sleeping nearly 24/7 for a while and then passed quietly in her sleep. I hope that your grandma has just as peaceful a death as hers was. I know it is so hard when you are constantly worrying, but know that we are praying for you and your family as you go through this difficult time.
I applaud her strength to say no to the hospital and to take charge of her life and her passing herself! Something tells me she has been a good role model for you. You are blessed to have a grandparent ( I never knew any of mine and wish I had had that relationship). I hope you have a wonderful relationship with her. Remember, while the body does not live forever, the love that a person imparts to this world can live on in those who remember them and use it for inspiration.