Great job rescuing this (hopefully) hen! If you do decide to keep her, chickens really don't like living alone and you should probably get another couple to keep her company. A 50 lb bag of grower feed costs about $15.00. That would probably last several weeks for 3 birds. (I'm guessing because I have 46 chickens and go through about 75 lbs a week).
Good luck with whatever you decide.
Good luck with whatever you decide.