My husbands ex wife keeps threatening to put a restraining order on me to keep me away from the daughter they had together. My husband has full custody of the child. She has no reason other than she doesnt want me around her daughter.
In law school I learned that anyone can sue you for any reason at any time.
However, it does not mean that the person will win their lawsuit.
Unfortunately, if she files something, you will need to go to court and defend yourself.
If someone (a process server or constable) comes to your home or office, accept the papers. Don't try to evade service. Just get the papers and run to an experienced attorney.
If Dad has custody of the child, then Dad will be involved too.