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

Here is Why You Need An Adapter

The outlet and plug type used in Mauritius are C and G and in Tanzania are D and G. This is how they look like.

Tanzania

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

Type D

Type G

Mauritius

In Mauritius, outlets of type C and G are in use.

Type C

Type G