To add - I would never, ever consider, or expect to even know, the financial situation of every guest, in order to decide whether I should ask for money from them to host them a meal.
Either I'm happy to host, or I'm not.
How do you know the ins and outs of all your kids financial circumstances? I don't really think it's your business if they're all adults, especially ones living independently.
It sounds to me like you've build up some resentment about the amount of money they get, and them eating at yours, using gas/electricity, and taking food back home with them. My mums genuinely very poor and just would never. You are their mum.
Stop them taking food from your house, stop feeding them as much at other times - yes, Christmas dinner contribution, no, in my genuine opinion. It's the time of giving, not taking. But, it does go for them as well. It sounds like they're overall taking a bit much, and it's getting to you. In which case, just stop.