@chicalot
I know some folks that would bring a bird inside if they were in that condition. I may just be one of them but I've never had to decide that before.
The fact that she's molting and was wet too would weigh a lot to me. Especially if she were by herself shivering. Yep. This hard-stance, no heat in the coop person would probably bring her in and a
buddy with her.
The other consideration, however, is that once she's in, you may need to keep her in for a long time depending on when your weather warms up enough to put her back out without total shock to the system. I probably wouldn't re-introduce her out until it was closer to 30 degrees.
Unless...you have some kind of "half-way" area where you could keep the temps warmer but not as warm as indoor temps - say around 25-30 like in a garage or enclosed porch...then it wouldn't be such a shock to the system to re-introduce her (them) to the cold.
All this is just an opinion and should be taken as such