You Do Need power plug adapter while traveling from Gabon to Mozambique.

Here is Why You Need An Adapter

The outlet and plug type used in Mozambique are C, F and M and in Gabon is C. This is how they look like.

Gabon

In Gabon, outlets of type C are in use.

Type C

Mozambique

In Mozambique, outlets of type C, F and M are in use.

Type C

Type F

Type M