Thank you all for your kind thoughts.
I appreciate all of the information very much. Sounds like Delta will be able to take care of this in a relatively painless manner.
Yes, we thought of the idea of keeping the account open. Unfortunately, we don't have his PIN. I have requested that it be sent to his address, but that will take a couple weeks. We may end up doing this for the other airlines and hotel programs he was in (US Air, Continental, United, Marriott, Hilton) if they end up being uncooperative.
Thanks again for the answers and the kind thoughts!