Welcome to Cartaholics.
Make sure the castle nut that holds the hub on is tight. If the nuts loosen up it can cause a squeak and eventually you'll strip the splines in the hub. If the nuts are tight it check your brakes or possibly the wheel bearing.
I think EZGO calls for 80-90 ft lbs on the hub nuts. Once you torque them don't back them off to get the cotter key in, tighten them until the you can get it in.