There is no "sure fire way" to do anything with chickens. Actually with any animal, mineral or human. But with chickens especially. They do their own thing.
Someone suggested that she might be broody and that is a distinct possibility, since she thinks she has been bred by your gang of young roosters. There is a way to tell for sure if she is broody, however. Pick her up and check her chest area. If she has pulled the feathers from her chest down to midway to her legs she is broody. Hens do this to put their skin directly on the eggs for heat and humidity. Do you have some fertile eggs around? Give her 2 - 4 eggs to sit on. If they hatch, great, if she abandons them before they hatch, oh well....you didn't really want chicks this late in the year anyway, right?
Now you are going to ask me if there is any way to break a broody hen of her hormonal response to having a nice place to live and therefore she wants to settle in and raise a family. Of course the answer to that is "nope". No sure fire way to do that. The only way I have ever been successful in breaking a broody is to have her eggs hatch. I currently have a hen sitting for her THIRD 21 day stint in a ROW, to hatch some babies. (Someone keeps breaking her eggs and she won't be moved from the favorite nest box. Grrr) However, others report that putting the broody hen in a cage with no real bottom, just wire mesh works. Some say putting her in ice water works. Some say moving her to a different coop works. As you can see, everyone has a different idea of what might or might not work.
Now if she has all her chest feathers and is still sitting there looking lost, that might be the best way to make her Senior years golden. Just let her sit and provide the rest of the flock an additional choice of nest boxes to lay their eggs in.
Let us know what you find out. And blessings on you for taking in these homeless f birds.