In these lines, the character that appears to be the antagonist is the mother. The protagonist of a story is the most important character, and the one whose story we are following. This would mean that Hansel and Gretel are the protagonists. The antagonist, on the other hand, is the character that opposes or is in conflict with the protagonist. This would be the mother, as she wants to let her children starve in the forest.
im gonna be labeled racist for this but some of them were good in their own right, multiple of our founding fathers (including George Washington himself) had slaves. Do you see people trying to go against the very man that is a huge reason the US exist? so no