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

Here is Why You Need An Adapter

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

Nepal

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

Type C

Type D

Type M

Mauritania

In Mauritania, outlets of type C are in use.

Type C