The diagram shows three blocks and two springs. A massless rigid rod has connected the "end blocks”. Now, the middle block is given a velocity v. The maximum deformation of the spring is [mass of A=2M, mass of B=M, mass of C=M. Horizontal surface is smooth]
At the time of maximum deformation in the springs all the three blocks would be moving with same velocity.
Let this velocity is v1. From momentum conservation