Very simply, the men in the poker game were overcome by greed and envy. Having lost $1 to Fleur for so long, they suspect that she must be cheating but have no evidence of it. When they decide to raise the stakes one night, in the hope of winning back the money Fleur has won from them, she wins the entire pot, enraging the men, particularly Lily. He had a plan to trick her and lost instead. He and the other men get drunk and decide to attack Fleur, to teach her a lesson. Of course, this backfires. They do catch her, but with Pauline's help in trapping them the next morning, they also lose their lives to the weather.
This confrontation highlights both the themes of sexism and of female power. The men can not handle that a woman has beat them and must "teach her a lesson." They must exert their superiority over the "weaker sex." And they do, attacking and possibly raping Fleur. However, it is ultimately the women who not only survive, but have the last word. Pauline traps the men, and Fleur goes on to live a long life.