Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
MOIST
As described in historical dictionaries
Patronymica Britannica (1860)
MOYCE. MO YES. MOIST. A probable corruption of Moses, formerly written Moyses. A Moyses is found in the Domesd. of Somerset.