The theme that best connects to this excerpt is "Evil can never truly hide itself."
Explanation:
"The Strange Case of Dr. Jekyll and Mr. Hyde" by Robert Louis Stevenson is a story that fully represents the conflict of good versus evil, and how the second one finds the way to leave its mark even when it has been sent away. These lines a clear example of this theme as the main character has to carry the heavyweight of the actions of his evil counterpart.