I went to the Columbia Co. Courthouse today and I did not find your Mary and Ira Hall. I did find 2 Mary Hall's . One died in 1892 but her husband was WM. The one who died in 1899 was married to Henry Hall.
The Ira Hall I did find was born May 29, 1862 and died Aug 13, 1924. Parents: Geo Hall and Louis Randell. Informant was Frank Hall of Poynette. The cause of death was suicide by firearm and he was buried in Dekorra (near Poynette) and the undertaker was from Poynette. I don't know if there is any connection here with your family.
Sorry I didn't find anything