Suggest Treatment For Parkinson S Disease, Diabetes And PTSD

My husband is 75. He has Parkinson s and diabetes and PTSD. He has also had a few very small strokes. He has been eating very little but still drinks some liquids. Lately he has only been urinating once or twice a day. He refuses to go to the dr but is supposed to have surgery on his back next week. What is the urinating problem and do you think he should have the surgery?