Sentence, an incorrectly written sentence, but a sentence.
Prince Escalus appears in Acts 1 and 3 to end the duels between the families and to hand out appropriate punishments to the people who have been fighting. He is also a mechanism for the audience to know or learn specific details of the brawls that may have been missed. In both Act 1 and 3, Benvolio recounts the fights to the Prince.
Escalus gives punishments that will significantly change the fate of the characters, and, if those punishments had not been given, would significantly change the direction of the play. His ruling that anyone caught fighting again in Act 1 would be killed, makes Romeo's banishment in Act 3 necessary, thus forcing his and Juliet's actions in Acts 4 and 5.
Her mother is her final opponent because her mother had so much more power over her and she wanted to break free. Also because she imagined her mother to be her final.
