My Mom z”l taught me to always take a gift when invited to someone’s home for a meal. I did so even as a teenager.
When my wife is home and we go out, we either take a bottle of wine or a tray of made-up goodies as a thank you.
When my wife is away (as she’s now in the States), I give her a list of where I’ve gone for Shabbat meals, and she brings back gifts that I take to the various families upon her return.