Policeman riding on motorcycles as guards to a VIP

Answer: Option A

One word substitute is Outriders.

Outriders: a person in a motor vehicle or on horseback who goes in front of or beside a vehicle as an escort or guard.
Servants: a person who performs duties for others, especially a person employed in a house on domestic duties or as a personal attendant.
Commandos: a soldier specially trained for carrying out raids.
Attendants: a person employed to provide a service to the public in a particular place.