Because ghana was a matrilineal society who was supposed to become king when the old one died

In a matrilineal society, the subject's female relatives are the ones to inherit or come to the throne.

If the king dies, one of her daughter will become queen.

Matrilineal" means property is passed down through the maternal line on the death of the mother, not that of the father.

The Akans of Ghana, West Africa, are matrilineals. Akans are the largest ethnic group in Ghana.