Be sure they have a draft free coop to go into.
Offer water (outside for less mess) 24/7 if you can. Feed at least 16% protein and whole corn. The corn will help build up body fat which will help keep her warm. I start to increase their corn intake in Oct when the weather starts to change. That way they are ready for the cold before it gets here.
Hay or straw bedding, deep if you can, helps too. They will nestle into it and it will keep them cozy
Anconas as a breed are VERY cold hardy. I'm in Maine and we have cold, snowy winters. I rarely lose one to the cold. It will be below zero and snowing and they will be out "foraging" in the snow. I only leave them cooped if it's below zero, snowing, AND extremely windy. Otherwise they are outside every singe day!