When a golf ball is dropped to the pavement, it bounces back up. is a force needed to make it bounce back up? if so, what exerts the force?

The coefficient of restitution is a measure of the interaction of the ball with the material of the ground. Since the ground is too solid to move (usually), or give way, the energy of the ball-ground system must be conserved in the main. Some of the energy is released as sound waves but the rest is given to, or reflected back to the ball and it follows the path of reflection. When the ball is dropped vertically it returns along the same path. So the force is actually the potential energy created by dropping converted to kinetic energy on collision with the ground. This is the origin of the force making it bounce.