My father's has an advance directive living will through the VA to be resuscitated, feeding tube etc. We were locked out of hospital account by the wife. We was his biology kids. She unplugged his fibulator without us knowing, put him on hospice and took him home without any kind of medical equipment and she was administering him the morphine her self. When he stopped breathing there wasn't even any equipment to take his heart beat or anything. Then she didn't call paramedics, she called the coronor. They asked her if he had a resuscitation order, she said no.
Hospice does not give extraordinary measures. Like said, a DNR is required. Your Dad needed to be considered terminal. That he was dying from what he had within at least six months. Hospice can go longer. What I am trying to say is that your Dad was probably dying. To resuscitate him or put a feeding tube would just have prolonged the inevitable. Feeding tubes are not all that great.
It may help you to talk to someone at the Hospice. They do help family after the fact.