My grandfather fought Parkinson for 15 years, 5 of which was a rough road. He passed away at the young age of 69. He had a terrible fall as well which landed him in the hospital and finally to the nursing home. He passed away about 6 months after his fall.
Be with him through these next weeks, spend as much time as you can with him. Even if he is sleeping, say your peace to him and anything you may want to talk about. If he is in a state like my grandfather was he most likely cant talk very well. However he can listen, share your favorite stories of times you two spent together. It may not seem like much but it will help and most likely mean the world to him.