You Do Need power plug adapter while traveling from Mauritania to Nepal.

Here is Why You Need An Adapter

The outlet and plug type used in Nepal are C, D and M and in Mauritania is C. This is how they look like.

Mauritania

In Mauritania, outlets of type C are in use.

Type C

Nepal

In Nepal, outlets of type C, D and M are in use.

Type C

Type D

Type M