Mr. Rushworth's overprotective mother causes some serious problems for Maria Bertram by the novel's end. The narrator hints that Maria behaved pretty badly around her mother-in-law, Mrs. Rushworth Senior, and there is probably a good lesson there about not acting terribly to your in-laws. After all, before the wedding, Mrs. Rushworth was quite friendly and gave the Mansfield crew a nice tour around Sotherton when they came to visit.
Maria's behavior certainly comes back to bite her in the butt since Mrs. Rushworth decides to let everyone know that Maria has run off with Henry (rather than hushing it up as Sir Thomas wanted). This effectively ensured the ruin of Maria's reputation.