Hi there,
Sorry to hear about your grandfather
While it is sad that he can no longer see (much) know that disabilities like this are by no means 'the end' of life. I have been in a wheelchair since I was 3 months old (gunshot wound) and I have always been very independent. I know what it feels like to think things are just so unfair because you can't do a certain thing on your own. I agree that depression must be dealt with, and I also agree that a dog could do wonders for him! Although, be careful with using the term 'helper dog' around him. If he is a proud man, he will most likely not warm up to this idea. He doesn't need a dog to show him how to live...perhaps. Maybe if that road turns sour just a dog in general would help. Bender is not much for carrying me up stairs, but he does wonders when I'm feeling down and need a hug.
Another idea maybe you could look online for associations for the blind around his area. It may help him to make friends that are dealing with the same problems he is. I have a few blind friends, and they are awesomely independent! I realize he's not a young whippersnapper anymore, but age (and disability) are all a state of mind. Good luck!
~LeAnn