In an emergency stop, the correct response is to press the brake pedal as hard as you can while also avoiding locking the brakes if you are driving a vehicle without antilock brakes (ABS). If your vehicle has ABS, you should press the brake pedal firmly and allow the system to handle the braking. Lightly tapping the brakes is not the most effective method in a true emergency stop situation. Using the parking brake is not advisable in an emergency stop as it can cause the vehicle to skid.
Therefore, the best practice in an emergency stop is to press the brake pedal hard while avoiding locking the brakes.