You Do Need power plug adapter while traveling from Vanuatu to Nigeria.

Here is Why You Need An Adapter

The outlet and plug type used in Nigeria are D and G and in Vanuatu is I. This is how they look like.

Vanuatu

In Vanuatu, outlets of type I are in use.

Type I

Nigeria

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

Type D

Type G