It's tough to tell right away. It could be that you have a muscle spasm, or you're stuck in an awkward position. Maybe you even had a dream that made you feel like you couldn't move.
Maybe you're too tired or something's holding you back physically. Hard to say exactly without more context.
Perhaps in a Christmas story you were turned into a snowman by a naughty elf and as part of the spell, your arms became frozen and couldn't move.
Maybe you got injured or were in a position that restricted the movement. Or it could be part of a magical or fictional situation in the story.
Maybe it's part of the plot to create tension or drama. It could be a magical curse or a physical injury.
Maybe the mom had other commitments or the plot didn't require her presence this time around.
Maybe she had other commitments or was out of town for some reason.
It could be that the focus of the story shifted away from the mom this time around. Maybe the creators wanted to explore other characters or storylines and didn't have much space for her.
Maybe there were scheduling conflicts or creative decisions made by the filmmakers. It's hard to say for sure.
It could be for a variety of reasons. Maybe the story needed a new dynamic or there were scheduling conflicts. Sometimes creative decisions are made to give the story a fresh twist.
The mom might not have returned for A Christmas Story Christmas because of travel difficulties, or maybe she wasn't in the right frame of mind for the celebration. Another possibility is that she had to take care of something important elsewhere.
Maybe the actress wasn't available or the director wanted to go for a different casting choice.