For the entire trip my brother refused to eat anything but peanut butter and jelly sandwiches. If those weren't available where we stopped he usually wouldn't eat anything at all.
That comfort food was one familiar thing when almost everything else in his life was changing.
Often when kids - and even adults - go through major changes in their lives it can help them adjust if they have access to a few familiar things. Those may be foods, bedtime rituals, or favorite toys.
What things were comforting to you when you were a kid?