Theoretically yes, the counselor could call the cops and ask the cops to come get you.
But so could your mother. There is no need for the counselor to get involved. For that matter, your mother could go directly to your uncle's house, and carry you, kicking and screaming to the car and take you home without the assistance of the cops.
Bottom line, no matter who makes the phone call, if you are living somewhere your mother does not want you to live and if she is still your legal guardian, then you'd better get your little rear back home because if your uncle is harboring you against your mother's wishes he is risking jail time. Counselor or no counselor.