"Be just then, O ye men of understanding! and mark not more severely what women do amiss, than the vicious tricks of the horse or the ass for whom ye provide provender—and allow her the privileges of ignorance, to whom ye deny the rights of reason, or ye will be worse than Egyptian task-masters, expecting virtue where nature has not given understanding!" (13.76)
Once she has shown that women's rights are perfectly rational, Wollstonecraft knows that men still might reject her arguments anyway. That's the thing about philosophical reasoning: because what you're talking about is pretty up to interpretation (what's the meaning of life? what is human nature? what are the rights of women, anyhow?) it's fairly easy to come up with a logically thought-out counterargument.
So in her final lines, Wollstonecraft asks men to have compassion and to listen to their consciences. Yes, they have the power to continue denying women equal rights. But they must realize that if they continue to do so, they'll be the Bad Guys of history, and future generations will look on them with disgust. She compares them to Egyptian slave owners, who, according to the Bible, got all sorts of nasty plagues—locusts: eeew, water turned to blood: double eeew—thrust upon them for their gross slave-owning ways.