I had a dream my grandfather was alive even though he has been dead for almost 25 yrs what does it mean ?

Most of the stuff that molds our personalities happens when we’re kids, and your Grandpa would have been (I assume) a pretty important figure in your early life. It certainly makes sense that he’d be tucked away in your subconscious somewhere.

It means the neurons in your brain were randomly firing, and the place where is memory is stored happened to be affected.

It means you wre thinking about him.

Well, maybe it is your subconscious, you were probably thinking of him or something like that, I have once read that dreams can sometimes reveal our deepest feelings and desires ( not all the time but it can happen). I have never met my grandfather, and yet there was a time when i used to see him in my dreams and talk to him. I still do not know how it happened, but it did, so I just think it is normal.

he was visiting you.

it means that you had a dream with your grandfather,dreams are random

It does not mean anything.