Huh. If it is Russian, I'm guessing it originated as a diminutive, since I don't know of any Russian feminine names transliterated with the ending "-ok" (other posters had guessed the name was Hungarian).
Perhaps it's derived from
Matrona, in that case?
Please rate my personal name lists:
www.behindthename.com/pnl/69381www.behindthename.com/pnl/69381/109399www.behindthename.com/pnl/69381/91835http://greens-end.myminicity.com