Tootsie I think you have to be selfish this year. Your parents' refusal to travel is their problem, not yours, so they can either not see you, or drop that habit, this year.
I'd probably invite your MiL round on the proviso that she helps / is hands-on with either the food or the children (the choice of which is yours!).
Since having kids we've said that we aren't schlepping the kids about. Christmas is for them, and we aren't spending it travelling! It may sound harsh, but that's how it is. Anyone who wants to see us can come round, but don't expect us to travel!
(My own, non-travelling, parents live about 3.5 hours' away...down near Woolly! Thankfully they understand our approach and we do go down during the festive period.)