Mother and child figure represents the female ancestor taking care of her descendants. This commemorative figure would have been used to honor the maternal spirit who in turn brings prosperity and fertility. Among the Kongo people, the woman is considered as the chief of the family. Thus, the female ancestor is the guarantor of the fecundity and continuity of the clan or family. Such sculptures would be kept on a family or local shrine where she would be receive sacrifices and offerings.
Article and image taken from, http://sm76626.wordpress.com/category/african-tribes-objects/