I don't remember much, there was this rich lady that I think was upset about her daughter or son getting married and her maid was always making these wise cracks that where really funny. I think the rich lady had a allergic reaction from something (maybe peanuts?) that were put in her food. I don't really remember anything else.
You might be talking about Monster In Law from 2005 about a mother (Jane Fonda) who disapproves of her son's fiancee Charlie (Jennifer Lopez). She has a wisecracking assistant (Wanda Sykes), and in the scene below, they fight when the mother intentionally puts nuts in the gravy, knowing that Charlie is allergic to them: