Finally, after all these years, I know what it stands for.

Miller & Holmes, Inc. began in the Twin Cities in 1896 as a wholesaler of butter, cheese, eggs, fruit and produce. In 1907, the company opened a creamery and added poultry to its product line. The first M&H Gas Station opened in 1931. In 1945, the company discontinued its butter and poultry business to concentrate on selling its M&H brand of gasoline and diesel fuel.

A Fargo-Moorhead mainstay for years. I think there's still one around, at least. They had a brief run selling hamburgers as well. Because why not?