Must children have hiphenated names since it's parents are not married or common law?

I believe that is an option that you as parents decide. It is not required if that is what you are asking.

I don't think so, my niece had a baby and she decided put put the baby's last name the same as the fathers. But she could have put her last name on birth certificate. Now he's a loser and doesn't have anything to do with the child.

If you use the fathers last name.. he must sign papers claiming the child is his... other wise you have to use your maiden name. You do not have to use both names. At least this is the way it works in my state.

No,
You may use just the mothers last name

You may use just the fathers last name ( but he has to sign the birth certificate.

Actually most people at least in our areas don't use the dual name hardly ever