A coworker had this problem last year; her job is secure, but she has three high-needs sons and an unemployed husband who was very down-in-the-dumps.
A friend and I bought misc. $10-25 gift certificates for Pizza Hut, grocery store, drug store, and fast food restaurants. We figured they could buy necessary basics, and either enjoy family meals so the kids wouldn't realize the severity of the family's financial situation or, if necessary, the kids could give the gift cards to friends as presents.
Then I got her a $200 gift card to Target so she could put something under the tree for her own sons and husband. I think it helped their family have a more normal Christmas which helped lower her stress level.
I made sure she had these anonymous gifts from the elves about 2 weeks before the holiday.
It was a stretch to spend the money that I did --- but I also felt there was no better recipient than her and her family. My kids may think they don't have enough Polly Pocket and board games, but they really do.