What to Have on Hand for the New Owners

Owner’s manuals and warranties for appliances left in the house.
Garage door opener.
Extra sets of house keys.
A list of local service providers — the best dry cleaner, yard service, plumber, etc.
Code to the security alarm and phone number of the monitoring service if not discontinued.
As a courtesy, you could provide numbers to the local utility companies.
If it’s a condo, leave information on how to contact the condo board.