My Cousin Has Dry Gangrene Of The Left Foot Severe

My cousin has dry gangrene of the left foot severe knee pain type 2 diabetes vascular dementia heart condition and advance local prostrate cancer. He is currently in hospital and Dr's cannot help so want to send him home. Please can you tell me his life expectancy as they are hiding this. He also has a catheter in now due to urine retention and his PSA level has risen from 0.8 to 15.9 please be honest.