Time of the Wolf (2003) on Netflix

Plot summary

After an unspecified disaster, Anne Laurent and her husband Georges bring Eva and Ben, their children, from the city to the family's rural vacation home. An armed man and his family have already moved in. The intruders allow Anne and the children to leave with only a few belongings, and the family wanders the countryside. They pass villages that are abandoned or hostile, and they see livestock burned on pyres. Other survivors refuse or are unable to help. On the road they meet a teenage boy who has lived by himself in the wild.