All I found was this old listing on Reverb:
It probably looks like yours. No date given, but the same labeling.
I've done a bit of looking in Jean Ritchie's Dulcimer People and not found a maker working under that label name.
No date or anything else. Mysterious!
Is there, by any chance, a date on the label?
I bought a used Dulcimer and can't find out anything about it on google or this group search. Inside it says:
The Original Mountain Music Dulcimer, Another hand crafted product of MUSIC CRAFTS of California, Los Gatos, CA 95030