Why does Maurya surrender to this power at the end of the play?

Maurya surrenders because there is nothing left to fight for. All of the men of her family have been sacrificed to the sea, and Bartleby's death has left her without hope. Thus, she prays that the souls of her husband, her husband's father, and four sons may rest in peace, and she resigns herself to her fate, claiming that she will finally sleep at night because she no longer has anyone to worry about.