I’m sorry that it may turn out that she loses all of her toes. Chickens can survive and get along on 2 stumps if they are about the same length. A lot of this decision is up to you, with how she will be able to get around, how much time you have to care for her, how special she is to you, etc. Since frostbite results take a month or more to be seen, you could wait and see how it turns out. There are a lot of threads on BYC about chickens who have lost both feet. People sometimes just let the chickens be, and they get along okay, while others baby the chickens or make special pets. Culling may be best for some folks, especially if things are not working out. Let us know what happens.