Remember to be patient and wait for him to talk. He may be taking pain meds that cloud his thinking a bit, so remember to relax and let him find the words to talk. I agree with Bill that he might have a special request for you. You could prompt him (if necessary) by asking if there's anything you can do for him.
Also it would be good to say you've enjoyed knowing him, and enjoyed having him for a neighbor, and you will miss him. And a long hug would be very cool.
_