After Marge's catches Gaear stuffing Carl's body into the wood chipper, she arrests him and saves the day (well, sort of, considering how many people are dead), lectures him on the stupidity of committing murder for a little money, and winds up triumphant and safe at home.
Unfortunately, her husband Norm didn't get the prize he wanted in the stamp picture contest. But, while watching TV in bed, Marge cheers him up, saying that people use the three-cent stamp whenever the postage goes up. They express their love for each other and reflect happily on the child they'll be having soon:
NORM: Two more months.
MARGE: Two more months.
This vision of domestic bliss stands in total contrast to a world where people meet hookers in seedy motels, plan kidnappings of their own wives, and get fed into wood chippers.
Marge doesn't do that kind of stuff: she works hard, takes comfort in her husband and future child, and holds onto her small town values. The movie ends with a corny but sincere vision of happiness and security. The Gundersons are getting it right in a way that Jerry, Carl, and Gaear simply never understood.