A rigid ball of mass m strikes a rigid wall at $60^\circ$ and gets reflected without loss of speed as shown in the figure below. The value of impulse imparted by the wall on the ball will be :

MV

Force applied by the wall will be along its normal hence component of momentum along tangent to the wall will remain unchanged.

Change in momentum will be along the normal direction 

⇒ $\Delta P = P_f -P_i$ = MVcos$60^\circ$ - MV (-$60^\circ$) = MV