An excellent golfer can provide an impulse of nearly 2 kg m/sec impulse to a 0.045 kg ball. What momentum and speed result from such a hit?

The momentum gain, which equals the final momentum, also equals the impulse, 2 kg*m/s.

Divide that by the ball's mass for the final velocity after the hit.

I get 44.44 m/s = 160 km/s = 99.4 mph

Actually, the golf ball speed record is about 200 mph. This golfer is not "excellent".