Without more context, I would use the word "masters."

If you say, "Women are the Masters of Men," two possibilities come to mind. Either a woman has written this to declare women's superiority over men, or a man has written this to lament the fact that men and women have reversed traditional roles in today's society. In my opinion, this is the "safest" translation because it allows for both scenarios.

If you Google the phrase, you can see how people have used it in different contexts.

Regarding some of the other suggestions:

If you say, "Woman is Superior to Man," this does not fully allow for the possibility that a man wrote it in the above context.

If you say, "Woman is Man's Mistress," this could imply that women are there to serve men sexually. It is true that "mistress" is the feminine form of "master," but the word is more commonly used to mean the woman a married man is having an affair with.

If you say, "Woman is Man's Queen," this means that men treasure and serve women and does not imply that women are superior to, or dominate over, men.

You said that this is a title, but perhaps you could share where the title came from. Is it the title of a book, a chapter in a book, a sub-heading in an article? If it is a book, is it a religious book, a feminist book, or even a novel? Such details might make a difference.

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Note added at 1 day10 hrs (2012-09-24 03:41:46 GMT)
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Your suggestion is grammatically correct, but I feel it is more natural to say "Women are the Masters of Men," especially as a title.

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Note added at 5 days (2012-09-28 05:21:51 GMT) Post-grading
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Glad I could help!