I've done a couple of these type of old folks residences in the past. I make a point of asking the attendees before hand where they come from and who is/was their favourite singer. I then (if possible)sing a song from their home town or area or do a song by their favourite singer. Afterwards, I always thank them individually for coming to hear me.
FWIW, I never ask for a fee or expenses, however that item is entirely up to the performer.