Hi Ashish!
It may be a little difficult for you to control the quality of food that you are eating now , but do not take stress about it.
Try to take one fruit daily with a hand full of dry fruits. These items can easily be stored in your room.
Along with the food provided at your mess, I recommend that you add cucumber, carrot , curds and 1-2 cups of green tea daily. This will improve your immunity and health.
However, you need a detailed assessment and Suitable diet plan to support long term immunity development.
Next Steps
Eat well, take fruits ,green tea and vegetables daily. Consult on practo.com for further advice
Health Tips
Avoid over the counter medication/multivitamins/supplement to build immunity -don’t take without a prescription.