What is it that the women do that drives montag over the edge? to what does he compare them in his mind?

Montag is sent over the edge when the women begin to talk politics. It is clear from their discussion that they voted based on trivial, materialistic factors rather than the candidates stance on issues. He listens to the discuss how they voted based on the candidates' looks, names, and mannerisms. It drives him over the edge and he compares them to monsters. He says, "did you hear these monsters talking about monsters?"

Before he is driven over the edge, he "stood looking at the women's faces as he had once looked at the faces of saints in a church he had entered when he was a child."