What to get old couple down the hall

My husband and I have been staying at an apartment building for a couple weeks until we move into our new apartment next Friday, and an old couple down the hall met our 2 year old last week when we were coming back from shopping and have been bringing her stuff that their grandkids have outgrown, like a toy stroller and a toy baby crib, and they just brought her the cutest glass kids tea set. We want to get them something as a thank you before we move out but we arent sure! Any ideas???