Rosaura's insistence on going to her friend Luciana's party generates a good deal of friction between herself and her mother. Her mother doesn't want Rosaura to go to what she describes as a "rich people's party." Furthermore, she doesn't regard Luciana as a true friend to Rosaura. All Rosaura is to Luciana is the maid's daughter and nothing else.
But Rosaura doesn't want to hear any of this. In fact, she's really rather upset at her mother's words, so much so that she yells at her to shut up, claiming that she doesn't know anything about being friends. Even so, Rosaura's mother doubles down, accusing Luciana's family of being liars for claiming that a magician will bring a monkey to the party.
Despite her skepticism, however, Rosaura's mother makes sure that her daughter's well turned out for the party. She starches Rosaura's Christmas dress and rinses out her hair in apple vinegar so that it will look nice and shiny.
As it turns out, the party ends in humiliation for Rosaura. Whereas all the other children are given gifts, she's offered money. It seems that Rosaura's mother was right all along; to Luciana's family, she's just the maid's daughter, and nothing more. In response to this humiliation, Rosaura instinctively seeks comfort in her mother and she presses herself against her body. This hints at some kind of reconciliation between mother and daughter.