Is answer C right, if so, please explain?

With no friction at the wall or the floor, diagram d would be a good representation.

i.e. The forces X and Y are normals, i.e. act at right angles to the surfaces.

However, if a frictional force acts at the floor it will oppose motion, hence point towards the wall, preventing the ladder from moving away.

Combining the force Y acting ↑ and the friction acting →, we have a resultant acting ↗

Similarly, if a frictional force acts on the wall it will oppose motion, hence point up the wall, preventing the ladder from moving down the wall.

Combining the force X acting  ←  and the friction acting ↑,  we have a resultant acting ↖.

Hence, diagram c shows this with X acting ↖ and Y acting ↗.

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