You can call me NIK
Offer to watch her daughter. She likely has a million things to do that would be easier without a little one underfoot. She may also need a break so she can just rest. You could "borrow" her daughter for lunch or something, giving her a little time to herself.
Bring over some holiday treats - cookies, etc. She might not be up to doing the decorating, baking, etc.. You could also offer to help out with any shopping or errands - make it casual by giving her a call and mentioning you're heading to the store and can pick up anything she might need?
“The most difficult times for many of us are the ones we give ourselves.”
― Pema Chödrön