Let her work through it by herself. I worked predominantly with males in a hostile working environment (location rather than ppl) it may well be she’s clever but perhaps she’s not showing common sense ? They probably see her as a daughter or grandchild just like yours seeing her as a mum ? If you say anything you’ll make the situation worse probably, if the environment is as you say she had every opportunity to not work their through a choice, however she is so she will have to navigate it.