Who is Madame Horcada from Waiting for Anya and what is their importance?

Madame Horcada is a widow who lives isolated on her farm just outside the village where Jo lives. Everyone in the village calls Madame Horcada the Black Widow because of her standoffish behavior. However, it turns out that Madame Horcada is braver than them all because it is she who hides Benjamin and the Jewish children he helps to cross the border.