heatherjulie,
Yes, that's the family. They had a further son, Ernest, born November 1901 so after the census. I don't know who the Margaret Smith is; another daughter? Sister to William? Smith isn't an easy name to research.
This is not a public grave so I'd be surprised that there is no connection between everyone in the plot; unless it was some sort of financial arrangement to save the Smiths funding a new grave! Burke was the first occupant.
Regards