Can i show field for only one category

Thanks for your concern.
The motive and the idea behind the module is to provide the ability to extend the contact form such that you can collect additional information from your visitors. So the module is developed with keeping very general requirements in mind. You can use jquery to hide fields depending on the category selected by visitors. I'll definitely keep this in mind and I hope I can provide such a solution.

Thanks again for your concern and wonderful idea.

Regards.