“I would say to you: Would you ever forgive me for that accident, for the death of your sister; would you ever forgive me, for I could never forgive myself!”
Dorothy said nothing. Oz had not kept the promise he made her, but he had done his best. So she forgave him. As he said, he was a good man, even if he was a bad Wizard.
She is protected by the Power of Good, and that is greater than the Power of Evil. All we can do is carry her to the castle of the Wicked Witch and leave her there.