If a company has a certain dress code, then she should either comply or find another job.
Years ago I was looking for a job and went to Disney to fill out the application. I have a mustache and have had it for 30+ years. I was told I would have to shave it off if I wanted to work there. I found another job. Didn’t cry or stamp my feet. Hey, sometimes you can’t have it your way. If that’s the case, find something else and move on.