Unfortunately, I don't currently have a listing in my chronology for Houdini's appearance at the Grand Opera House in Bellefontaine. This doesn't mean he wasn't there. I've just yet to find him.
The Grand Opera House operated from 1880 to 1913. As far as I know, Bellefontaine was not on the Keith or Orpheum vaudeville circuits, so it's most likely Houdini appeared here in his early days (1893-1899). Opera Houses such as the one in Bellefontaine are where the American Gaiety Girls, California Concert Co., or Roger's Orpheum Stars would play, sometimes only for a single night.
So if can anyone help find Houdini in Bellefontaine, that would be great. That sign is too cool to not be true!