Mess food at NIT Trichy is decent enough. My friend is a student there. From what I heard, I can assure you that you will not be disappointed. There are separate North Indian and South Indian messes ( both Veg and Non-Veg) for the students of 2nd year onwards. Also, you can change your mess after the end of a month.
All in all, mess and nearby localities are enough to provide you ample food varieties. Whether you belong to any part of the country, you can get food of your choice easily.