A guy from my company posted a bad review of our company on Mouthshut where he wrote bad things about the company and named some female employees including me saying they do prostitution.
I know it was him, though I'm sure he'll deny it if challenged.
I would ignore who wrote the post entirely, as mixing up accusations in this isn't helpful. If your boss wants to find that out later, let that be up to him to resolve.
Mouthshut might not want to do anything with the bad comments made about the company, but they may well take down any comments about names of female employees doing prostitution. (They may not of course, but it's definitely worth a shot.) I would email them with a link to the review and ask that they at least remove the names of the female employees based on the above.
In parallel with the above, you should also make your boss aware of the post and ask him to instigate steps to get it removed, or at least the personal part (your names) removed. He may be able to escalate it up the chain of command, and get legal help if needed.