She should be alright. Just check on her, especially first thing in the morning and when they go to roost in the evenings and make sure she's out and about with everyone else and that she's roosting, too. They may not be as active as usual in the cold weather, but still moving around, eating, drinking, and keeping up with the general energy of the rest of the flock.
Our BR and DOM just started molting about 1.5 weeks ago (everyone else was done with that by November, but these two kept laying and hung on!). Our BR is mostly bald throughout her bottom, butt, and back and our DOM's head is bald, as are her sides and much of the bottom of her wings. They look AWFUL and this cold snap has had temps going from the low teens at night to the low- to mid-20s through the day time hours, and the chickens just don't seem to care. They seek shelter from any wind a lot quicker than is usual, but they're all out and about like it's not bone-chillingly cold.
The hen aprons don't provide much in the way of insulation, so if you do see her being slower/more lethargic/hunkered down in a corner shivering and acting like she's cold, I'd probably recommend taking her into an unheated garage or other fully enclosed area and setting up a pen with plenty of material (wood shavings or blankets/towels) for her to settle down into and maybe adding a small space heater or heat lamp (just enough to keep it from getting below freezing, but NOT making it so warm that she gets used to it and ends up in shock/struggling when its time to go back outside).
