To dream of a billy club represents combative and resistant thinking. It may also reflect feelings about a problem or resisting behavior you want to assertively set straight.
Negatively, you or some aspect of your personality doesn’t want to change, and is putting up a fight to prevent it. You may be very resistant to alternative views or opinions. It may also reflect an authoritarian mindset that believes it needs to “beat down” anyone that is not behaving the way it likes.
To see police with billy clubs symbolizes feelings about a need for heavy handed discipline. Change that is going to require some assertive control or aggressive interference.
Example: A man dreamed of seeing a man holding a bully club in both hands. In waking life his friend had said some very strong homophobic remarks.