Why does Tom choose to stay home in "Contents of the Dead Man's Pocket" by Jack Finney?

In “Contents of the Dead Man’s Pocket,” Tom Benecke stays home even though his wife is going out to watch a movie.  He has wanted to see this particular movie, but he thinks he needs to stay home and work. His desire to work and get ahead, even at the expense of enjoying his life, is the main theme of the story.
This story was written in 1956. This was during the height of the post-WWII boom where the American economy was going strong and men (very few women held good jobs) were striving hard to get ahead. This was a time when men did not spend much time with their families, choosing instead to work hard so they could advance their careers and thereby achieve more material security.
In this story, Tom is a real go-getter. He wants to work hard so he can be known as “the Boy Wizard of Wholesale Groceries.” Because of this, he decides to stay home and work instead of go to the movie he wanted to see with his wife whom he loves. He is giving up that sort of pleasure in order to get ahead. The story centers on what happens to Tom when he stays home and how this affects the way he thinks about what is important in life. The answer to your question, then, is that Tom stays home so he can get more work done and thereby advance his career and his family's material prosperity/ security.