I did a bit of a Google search on the title.
All I can find out is that is was taken ca. 1938 in CA.
As I look again at the hearse - it may be horse-drawn. Notice that the doors are hinged on the right like a carriage.
But why the "valley" reference? Central Valley perhaps and therefore a reference to the Okies? But would a dust bowl refugee have been able to afford a hearse?
Or was this a "native Californian" mourning not just a personal loss but the loss of a simpler, pre-Depression, pre-Okie way of life?