Gilbert, Sandra M. and Susan Gubar. "Shut Up in Prose: Gender and Genre in Austen's Juvenilia," The Madwoman in the Attic: The Woman Writer and the Nineteenth-Century Literary Imagination. New Haven: Yale University Press, 1979: 127-45.
Gilbert & Gubar argue that Northanger Abbey is a subversive "indictment of patriarchy," and base this on its relationship to the gothic genre and contemporary gender issues. Although it is clearly an old piece of scholarship, it was published by a university press, and is still a touchstone text on Austen. I would use their argument to talk about Northanger's relationship to Udolpho as a gothic novel, and argue against their claim that [fill in the blank].
*Example borrowed from Dr. Dowd-Arrow's ENGL1102 class.