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

Here is Why You Need An Adapter

The outlet and plug type used in Vatican City are C, F and L 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

Vatican City

In Vatican City, outlets of type C, F and L are in use.

Type C

Type F

Type L