All I can say for sure is my own experience. My grandfather died a very long, torturous death from complications of Parkinson's Disease. This former Sailor and carpenter had lost almost all function of his limbs and they became spastic and stiff. His mind was fully functioning, but he was unable to speak in more than a whispered mumble. In the last weeks of his death, much of the family came together to keep vigil over him 24/7. With so many people in the house, you just slept where you could find a free sofa or recliner.
About a week after he died, I had a vivid dream that began with me sleeping on the living room sofa as I often did during those last weeks. I awoke in my dream and walked into the kitchen. Grandpa was standing there with the biggest grin on his face. His grin was so big, and his back was so straight and he was so strong-looking. He was the Grandpa that took us swimming and pitched wiffle balls to us kids, not the Grandpa that had been in so much pain. I also noticed at that point that I shrunk, and was now looking up at him as he is grinning at me. He handed me a dish of vanilla ice-cream with chocolate chips in it. He didn't speak, he just kept smiling. I thank God that this image will be engraved in my mind forever.
I've wondered many times what this experience was. Was it Grandpa's actual spirit conversing with me? Was it God giving me consolation during my grief? Was is just my imagination? I don't know and I'm not concerned about it. It was something good. And I'll accept it for what it was.
There's another one concerning Grandpa, but I've already wrote so much already! I guess this has been a good outlet for me.