Obviously MF stands for Motorized Focus
But I think MF isn't meant as "manual focus". Konica had several models in C35 family, like EF, EFP, EF3, AF2, AF3 and so on. Well, M could stand for motorized film advancing. Their first AF compacts, C35 AF and C35 AF2 were released in 1977 and 1980, repectively. Thus C35 MF, released in 1982, were their first AF compact with motorized film advance (so index MF) but later when all cameras became motorized they just dropped index M as needless. Sounds good?
What's important - MF model is noted as able to lock focus. I wonder if earlier AF and AF2 weren't?