Please solve this question and also explain what will the direction of frictional force and why?

Dear Student ,
From the energy conservation principle , we can find out that , 

maximum spring potential energy = maximum decrease in gravitational potential energy 
$$\begin{gathered} \frac{1}{2}k{x_m}^2=Mgh \\ here the h is also given as h = x_m\sin \theta \\ So , \\ \frac{1}{2}k{x_m}^2=Mg{x}_m\sin \theta \\ {x}_m=\frac{2Mg\sin \theta }{k} \end{gathered}$$

Hope this helps you .

Regards