Are you saying that they can or can't sit on the roof? If they do sit on the roof, then the men are below/beneath/under them. It could also be said that the men are lower than the women - though the sentence would have to written with care, as lower can also mean than the men are less, in some sense, than the women.
to answer your question: In Myanmar women can't sit on the roof of f.e. a bus.
I understand correctly that I could use all three? below/beneath/under them?
If I understand your explanation correctly I would say: "Women can't sit on the roof of a bus because it is a form of disrespect to the men under them. Unfortunately in Myanma society women are less then men."