Mrs. Hubbard is the elderly American woman who is always talking about her daughter – and she's played with gusto by America tragic actress Linda Arden. As her confession in the last chapter reveals, Linda Arden is the grandmother of the murdered Daisy Armstrong, and the mother of Mrs. Armstrong (Daisy's mom) and of the Countess. As a skilled actress, Linda Arden fits perfectly into what is characterized throughout the novel as a highly theatrical murder. A strong-willed woman, she offers to take the blame for the murder plot, declaring that she would have "stabbed that man twelve times willingly" (3.9.84).
Linda Arden's last name comes from Shakespeare's As You Like It, a play set in the Forest of Arden. That clue eventually gives away her identity.