There's a line between being neighborly and being a doormat. Your neighbors sound like maybe they are a bit lonely, and maybe also they either don't want to/can't afford to pay for a handyman to come and assist them instead. Unfortunately there's not always an easy way to find out which applies without offending someone. Does the couple offer to do things for you in return? Not big things, but something to show they appreciate it?
Perhaps your husband could speak to them and say look, I'm happy to help you, let's pick one night a week where I spent an hour or two to lend you a hand. How about Tuesdays? The rest of the week, I need to spend evenings with my family and give my lovely wife a break. If the neighbor persists on asking on other days, he could either remind him of the agreement by saying "I'll gladly look at that on Tuesday." or something along those lines?
Perhaps your husband could speak to them and say look, I'm happy to help you, let's pick one night a week where I spent an hour or two to lend you a hand. How about Tuesdays? The rest of the week, I need to spend evenings with my family and give my lovely wife a break. If the neighbor persists on asking on other days, he could either remind him of the agreement by saying "I'll gladly look at that on Tuesday." or something along those lines?