It is quite normal for squirrels in the wild to have squabbles over nests since squirrels are very territorial in nature. I'm sorry to hear your sweet wild friend Bubba is injured.
If you are able to get a picture of her leg, that would be really helpful for us to see the extent of the injury. Is she still able to get around fairly quickly and climb ok? If so, I would just keep a close eye on her supplement her with food as well as providing fresh water to help her keep her strength up. Thank you for caring enough about her to come here to find help.
Squirrels in the wild usually have two nests that they alternate between, so Bubba may very well have another nest somewhere near by. You could consider purchasing a squirrel nest box for her and mounting it on a tree nearby. My wilds all love the nest boxes but there is no guarantee that she wouldn't get ousted out of a box as well.
If she looks to really be struggling to get around, you may need to try and trap her. But it is very stressful on wild squirrels to be trapped, so you wouldn't want to do it unless you feel it is absolutely necessary. Fortunately squirrels tend to be fast healers and I hope that will be the case with Bubba.