Who is Head's "Nigra" Goddess, The African-American from A Woman Alone: Autobiographical Writings and what is their importance?

Head is fascinated by an African-American woman who emigrated from the United States to Serowe as a self-expression of care for the people of the area. She considers the woman a "Nigra" Goddess.... a woman from a land where her people were once oppressed, who've flourished nonetheless.