As an retired Probation and Parole Officer I am quite familiar with the situation being described here. I must say you have been give very good advice here.
I want to talk about your daughters position and again Bluerose is on the right track, that your daughter must be suffering from depression or at least a very low self-esteem, not being able to stand up to a person who is obviously harming her.
It may not only be a low self-esteem but a real fear of of being harmed by the other person. This should be watched. It often happens that women with a low self-esteem - primary sign of depression - will identify with her stalker. Despite their differences they may have something in common.
I usually aim at treating the woman's depression and then teach her Assertiveness training Program, as described in the following articles: