Definitely socks to echo other peoples' sentiment here.

Pre-paid phone minutes cards, because a fair number of people have phones but not necessarily a consistent plan.

Tooth brush, tooth paste, soap, deodorant, dry shampoo (will need to discern on your end if the gift bag is being given to someone with long hair or not), space blanket (the silver kind you unfold). If there are any grocery stores near you that you think those people would frequent, perhaps gift cards to that grocery store.

If you have a YMCA / gym near you (< 1 mile away) that sells one day passes that don't expire for a long time, perhaps you could buy some of those to give out and then people would have access to showers? That's something we could do for people in the midwest, not sure what the rules are like out here.