Who is Hannah Okonkwo from No Longer at Ease and what is their importance?

Hannah Okonkwo is Obi Okonkwo's beloved mother, Hannah, often argues with her husband about his excessive generosity. Known as "Janet's mother" from the time her first child is born, she becomes "Obi's mother" upon the advent of her fourth child and first son. Obi enjoys a special relationship with his mother, especially from the time she cuts her hand on a rusty razor blade that he leaves in a pocket. Hannah takes being a catechist's wife seriously, and orders the children not to accept food from neighbors for fear it has been offered to idols.