What to do????

When there's nothing to do. My Dad as I keep mentioning is in poor health. He has ulcers and is 79 years old and thinks he is just ready to die. He is now refusing to eat. He has lost a tremendous amount of weight and doesn't seem to think that it is making him weak. Yesterday he fell and my 78 year old mother struggled to get him back up. She is sore and tired today. I have instructed her to call 911 next time for help and then to call me and I will come to them. Whether or not she will, I do not know. The Dr. has asked him to accept some in home physical therapy. He has agreed but told my Mom that he is too weak and won't be able to do it so they are wasting their time. I spoke to the Dr. about depression and he put him on meds Friday so maybe they will get in his system in the next couple of weeks and maybe that will help. So far nothing has helped his attitude at all. I am at the end of my rope and do not know what to do. I know he is elderly but I do not see any reason for him to not be able to get better if he will just try. He has never been an easy man but now he is impossible. My poor Mother is there all the time. I am worried about her too. It is a very difficult time right now.