"How do SS expect her to answer a question that she honestly can't?"
TBH, an Abuser is an abuser. To the rest of us, we KNOW that this man will never change. We KNOW she has to keep him away from her , from you and from the baby. in any and every way she can.
HER past clearly HAS influenced her thinking on this. HOWEVER, if you have the chance to explain that due to ONE threat you had to act to save your DD, and that her Ex is categorically dangerous to her, to her unborn DC and to you. He/his family could do untold horrors to any one or all of you.
As far as a future plan I think the best thing is to say that she is going to act in the best interests of her DC at all times and that if (in accordance with the thinking of SS) that requires legal measures to keep him away from her, she will support that. If this Ex has a valid case and reason to be allowed contact through court, that she will also seek legal advice and see what the options are.
WRT the telephone call, you need to explain that SS will NOT trust her, the police and courts will not trust her if she is not 100% honest with them.
That call IS against the law, he is now intimidating her, he has no respect for the law, he's been inside TWICE, he knows the system. He doesn't care for her safety, her feelings or the consequences of authority. This makes him EXTREMELY DANGEROUS.
Is your DD with you? can you go to her? You need to remove the Orange sim and get a new number AGAIN.