In the 1930s Laura Ingalls Wilder wrote books about her childhood on the American frontier in the late 1800s. In the 1970s Michael Landon and Melissa Gilbert starred in a hugely successful TV show based on the stories. A zillion reruns later “Little House” has returned, as a musical. The production is up now at the Guthrie Theatre in Minneapolis, and Gilbert, all grown up, has been cast as Ma. Minneapolis theater maven Sarah Lemanczyck looked into the buzz surrounding the show.