If the block is displaced by a small distance x then what will be the time period of block?

Dear student 
Spring mass system is displace by x , 
So , last pulley will also move down by say x1.
Second last pulley will move up by x2.
Similarly , x3 and x4 distance to remaining two pulleys.
x = 2(x1)+2(x2)+2(x3)+2(x4)
-x = 2[2F/K4 + 2F/K3 + 2F/K2 + 2F/K1]
F = m*a 
a = w^2x 
w = sqrt(1/m(4/K1 +4/K2+4/K3 + 4/K4)
T = 2pie/w 
T = 2*pie sqrt(m(4/K1 +4/K2+4/K3 + 4/K4)
Hope this helps 
Good Luck