The collective noun for robbers is usually "gang" or "band".
Option A: "Crew" is used to refer to a group of individuals who work together on a ship or aircraft, or in a particular field or profession.
Option B: "Troop" is used to refer to a group of soldiers or a cavalry unit.
Option C: "Band" is a commonly used collective noun for robbers.
Option D: "Squad" is usually used to refer to a small group of individuals who work together on a specific task.
Therefore, the correct answers are A and/or B. Option C is the most appropriate answer.
The Answer is: C.