Why does mrs. frank accuse mr. van daan of being a poor father?
he is caught stealing bread while the children go hungry.
he is unable to peter with his academic studies.
he threatens to throw peter's cat, mouschi, out in the street.
he is never satisfied with peter and belittles him in front of the others

He is caught stealing bread while the children go hungry. While in hiding, food was always an issue and the three families of the Franks, Van Daan and Dussel stayed together and had little portions.

However, Mrs. Frank catches Mr. Van Daan one night while stealing bread and she gets furious with him while him of being a poor father.

it exposes the hypocrisy of religion and christian supporters of slavery