I saw this B&W movie as a rerun in the 60’s. There was a scene in the woodshed showing the father building a coffin for his wife (who died) and then for himself for when he died. The end of the movie showed the son (10-12 yrs old) pulling his little sister (3-5 yrs old) on a sled through the snow to an isolated but pleasant home in the country where the homeowners came to the door and greeted the little girl and took her inside. The ending scene showed the boy walking away from the house to an unknown future.
It isn’t much to go on but it certainly made an impression on me. Thank you for the help in identifying the movie.