Every Christmas, I take my two boys out with £50 worth of £5 gift cards, normally Greggs. We hand them out to the homeless on the street but don#t tell them how much is on it. That works far better than any of the options given, because it's not cash, it's not food which they may not want and they don't know the value of the card so can't easily swap it for cash or other.
I also put the gift cards through as a business expense so it's a tax write off, I feel epic, my boys learn a valuable lesson, but it doesn't actually cost me very much
TIL you can buy Greggs gift cards.