How does Sir Lancelot repay the noble woman who releases him from the four queens?

Sir Lancelot repays the noble woman who frees him from the four queens by expressing his deep gratitude and loyalty. He honors her by pledging his service to her and becomes her knight, demonstrating his commitment to her well-being and protection. This act of devotion highlights the chivalric values of loyalty and gratitude in the Arthurian legends.