When did huckleberry Finn's dad die?

Nearly all of the Grangerford clan is killed in a feud in Mark Twain's Adventures of Huckleberry Finn. In chapters seventeen and eighteen, Huck is separated from Jim. He ends up spending time with the Grangerfords, a family embroiled in a feud with a nearby, rival family, the Shepherdsons.

The Grangerfords include Mrs. Grangerford and Colonel Grangerford, his sons, Bob and Tom, his daughters, Caroline and Sophia, and the youngest boy, Buck. Before Huck meets the family, one daughter, Emmeline had died of natural causes, but three sons had been killed.

Buck explains to Huck how a number of people have been killed in the feud, including Buck's fourteen-year-old cousin, Bud, just earlier that year. He claims a Shepherdson was also killed earlier in the year.

Miss Sophia runs off to marry one of the Shepherdsons, and the families start battling. Huck meets up with Buck and Buck's cousin, Joe, by the river. Buck says that the Shepherdsons had ambushed and killed his father, the Colonel, and his brothers, Bob and Tom, earlier in the day. Huck watches from high in a tree as Buck and Joe are gunned down trying to escape by swimming in the river.

You can listen to an interesting and free audio rendition of chapters seventeen and eighteen at the link below.