I know this is difficult but, she should get copies (if she doesn't have them) of all her evaluations over the 4+years and review them. If they are good, she can contact the school for a sit down, or, perhaps better, the teacher's union to see if a rep. can help her out.
Did she let the school know she is looking for another job? If she didn't, that could be a problem, and it may re fixable.
Sometimes, you just have to find other references, or be prepared to explain your position, don't ever sign away your right to see references provided by any employer.
(I have seen this request on applications) Best of luck.
There are schools with good support and resources for teachers dealing with difficult situations. Some, not so much.