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

Here is Why You Need An Adapter

The outlet and plug type used in Tanzania are D and G 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

Tanzania

In Tanzania, outlets of type D and G are in use.

Type D

Type G