You think that your hometown has changed a lot since you were a kid? Just imagine how different it would be if it had been hit by the Black Plague.
Before the plague, Eyam is an idyllic country town. The people there are modest and well-meaning. The surrounding nature is beautiful. Even the local Puritan pastor is a genuinely good-hearted dude. It's the kind of place you'd see on a postcard, if they had had postcards in the 17th century.
Unfortunately, everything changes once the plague bears down on this tiny village.
The change is most obvious, at first, in the disposition of the villagers. What was once a tight-knit community is now paranoid and insane, with people accusing each other of dabbling in "witchcraft" and "spells" (2.13.82) on a daily basis. Eyam used to feel like a sitcom; now it feels like a horror movie. Even worse—it feels like a "wide green prison" (2.7.33).
The Post-Apocalyptic Plague
We can see the dismantling of this community in the physical landscape as well. The first whopper is when Mompellion shuts down the church and instead holds services next to the river. The community's main gathering place is now kaput; it's just too dangerous to be in a confined space like that.
In a similar way, Anna notes after the plague leaves town that "the road is grassed over, with just a cow-track down the center where the slight use of a few passing feet has worn the weeds down" (1.1.27). Nature has taken over.
Anna isn't going to see how Eyam ends up, however, because she lands in far-off Algeria. No, really. This might be unexpected, but it's her way of following her dreams to learn more about medicine and carve her own path in life. The mere fact that Anna ends up somewhere so far outside her comfort zone shows her immense growth over the course of the novel.