Sound works but no music?
A set of dosbox.conf settings which I can confirm works are those shipped with the GOG copy of the game.
[sblaster]
sbtype=sb16
sbbase=220
irq=7
dma=1
hdma=5
sbmixer=true
oplmode=auto
oplemu=default
oplrate=22050
You will also need to run install.exe (within dosbox) to make sure MoM's settings match the dosbox ones. Use Soundblaster pro (later) with 220 for the music, and Soundblaster Pro (later) with the dosbox settings above for sound.
If these do not work, try updating/reinstalling your copy of Dosbox.