In this story, I think it is quite clear that the protagonist is Maitre Hauchecorne. He is the one that we sympathize with in the story and he is the one we are really concerned with -- hoping things come out okay for him.
I think you can say that society (and specifically the peasants in general) is the antagonist. It is society that refuses to believe Maitre Hauchecorne and that eventually causes him to go crazy. The author thought peasants were too suspicious of one another and he is trying to show that by having peasants in general be the antagonist in this story.
Protagonist - Maitre Hauchecorne.
Antagonist - Manlandain
.......Manlandain is antagonist in this story.