Syini666: I'm no expert, but have gone thought a couple of these with people who were harassing my sister.

If the person in question is 18 year old, then that person would need to file for the restraint. If there is no legal reason, most likely the restraint will be denied. You can't get a restraint against someone unless there is a reason. Dislike for a person is not a reason. If someone is threatening another person, or there is reason to believe that harm could come to someone, then a restraint would be valid.

If someone is 19 years old, then that person has to legaly make all the decisions. A parent can't force anyone to do anything after 18 years of age.

In my case, my parents offer advise. If I choose to take it, then that is that. If not, then I learn on my own.

As others have said... this could have a negative impact on the mother/son relationship.
But... what has to be realized is that, after someone is 18, they are responsible for their actions, not the parent. If someone of legal age does something to get them into legal trouble, there isn't much a parent can do, except help find a good lawyer and help with court costs... if they are lucky.