Neat body. Interesting that there's no rear fender. That front fender looks like it's been around the park a few times.
I wonder what Demonets' was. The truck was probably a delivery truck, but it could almost pass for a poor man's hearse too.
Perhaps it was used for delivering this musical instrument.
From a Google search, it may apply:
Boyd's Directory of the District of Columbia
1908 - ‎Washington (D.C.)
1834 14th nw, h 1900 13th nw Demonet Jules (Demonet's), 1909 H nw DEMONET'S (.Miles Demonet), confectionery, caterer and wine merchant, showrooms ...
Henry that was my first thought..."it's a hearse"!!
Doubt it's a hearse. Even for the "poor man" you were displayed behind glass in a hearse. I have never met a mortician that wasn't proud of their work.