1For the first question C is the correct answer.
You can do this question by using your imagination.
If h is more, the mass will fall from a larger height and so the spring will be compressed more. So (a) is not the answer. compression .5*k*x^2 = mgh. So x will be larger.
The maximum kinetic energy of the block will be at the point just before the block touches the spring. Hence mgh = maximum kinetic energy depends on h. So, (b) is not the correct answer
The compression of the spring at maximum kinetic energy is zero. It is at the moment just before the block touches the spring. So it is independent of h. So (c) is the correct answer.
(d) is also similarly wrong.