This is part of the famous finale of this excellent and extremely funny play, when each of the male characters decide to perform a test to see which of their wives is the most obedient and respectful. Now, just think about the two sisters, Bianca and Katharina. Based on their actions throughout the entire play and the way that they have responded to the male characters, who do you think is going to show the most respect and obedience to their husband? Your answer reveals the massive irony of this ending - we do definitely not expect Katharina to be the one who comes, we would think that Bianca, who after all has shown herself to be mild-mannered and subservient throughout the play, and yet the quote you have highlighted shows that she does not come. Therein lies the massive irony of these events - the gap between appearance and reality. It appears that Petruchio has been successful in "taming" his "shrew" to such an extent that she is more obedient to her husband than her sister.