I would check with the churches in the areas where the Hubbards may have lived.
There exists any number of reasons why people who disappeared during an epidic or disaster have never been found.The two with which I have had personal experience are:
The epidemic in Comal County Texas where upwards of 200 people died. In the Old New Braunfels Cemetery is a very large mound which marks those buried in a common grave.Were it not that the pastor of the church kept a record of those who died and what became of the remains, we would have no idea who they were.
The second example represents a situation where we will likely never know. That is the 1900 hurricane that hit Galveston and surrinding towns and killed between 6,500 and 8,000 people. The exact nunber of dead is not known and will never be.With no place and no way to bury the dead, and fearing disease, these bodies were loaded onto ships and taken out to be buried at sea.Their names are not known.
In cases of epidemics and disasters, people are lost in more ways than one.