Poor Maria's death. Her father is obviously shattered when he's bringing her dead body through the streets, as was the Monster's horror at unintentionally killing her... and it's made only worse with the realization that from this point on, the Monster's existence will be one of unending misery and torment.
It's made even worse by what turned out to be their last conversation when they first appear. Maria asks her father to stay home and play with her, but he says that he can't and leaves. Imagine how he felt remembering that when he came home to find that she'd been killed while he was gone.
The Monster is terrified of fire and yet that's how he ends up killed. Yes, the sequel retcons that part of the plot, but considering this movie was not originally written with a sequel in mind, it's still a sad way for the Monster to go.
