http://hu.wikipedia.org/wiki/Magyarorsz%C3%A1g_telep%C3%BCl%C3%A9sei:_M
This is the list of towns and villages of Hungary beginning with M on the hungarian wikipedia. Feel free to skim-read it, but i have a hunch that i have allready found the village you are looking for.
There is a village called Megyaszó in Borsod-Abauj-Zemplén county in the north-eastern part of Hungary. There is no other that resembles the name you have written. If you know anyone who speaks a bit hungarian than the village homepage
http://www.megyaszo.hu/ might be of interest to you, if not you can still look at the pictures. It is a very ancient little village, it supposedly had a church back in the time of King Steven. It's name is said to be stemming from medveszó (literaly meaning bear-word, referring to the sound bears make, for the surrounding forest were full of bears), that was later corrupted to mediaszó, even later megyaszó. No bears left in Hungary anymore, so if you think about visiting you needn't bring a rifle
I hope i could help
Cheers from Hungary
Zoltan