Despite the dates on the gravestone in the first scene, it's not the 19th century; it's the present day, but the town elders have isolated themselves in order to raise their children free from the evil influences of the modern world. The monsters that haunt the village are just elders in suits, maintaining the fiction and keeping everyone scared. It's like Amish Country with teeth.
So when a young man in town is dying for lack of medicine, one of the town elders sends his blind daughter on a day-long walk through the woods to "the towns" to get medicine. When she exits the woods, they turn out to be part of a closely guarded "wildlife reserve," maintained, it seems, by her father, whose name is on all the security trucks, and whose father was a billionaire murdered by a business partner.
What's wrong with this guy? He spends millions setting this up and can't pay someone to leave a box of medicine in the woods? Or find someone other than his blind daughter to walk alone to the woods and negotiate for medicine with strangers in a world she is completely unfamiliar with? Or mention the fact that there are guards, and a wall?
As bobhowe noted, it would have been a better story had there really been something supernatural in the woods.
Author Margaret Peterson Haddix is considering a lawsuit against Shyamalan and Disney for appropriating ideas from her novel, Running Out Of Time, in which a young girl raised in a town where the elders have maintained the fiction that they live in the mid-19th century has to go to the modern world to get medicine.