Well, "ideally" / "traditionally" there would only be one competition. But since women are generally outperformed by men, separate competitions for men and women were made. Since she doesn't fulfill the "handicap requirement" that other women does, I suppose she could have competed in the mens competition. But then again, she might not be very good at it? And since she (at least socially) is a woman, it might not be easy to allow her to compete with men?
So, um..., if the boys will let her play with them, I guess she can? Other than that it is probably unfair to the other girls...