The documents that needed to be submitted before april 2 , 2019 are as follows:

a. Copy (not original) of Community/caste certificate, duly signed by Dy. Tahsildar or District Magistrate. If the certificate is not in English, an attested English Translation should be attached.

b. Application form for Undergraduate College Recommendation for Minority Network category for Christians along with required enclosures/certificates (refer Section 4.2)

You are required to send these with your application number clearly mentioned on it. If you don't mention the application number or the documents reach after the last date they won't be accepted.
So, please try to send them as soon as possible.
Any more details you need regarding the Application or admission in CMC College open the admission page of the college and download  the ADMISSION BULLETIN.I will provide you with the link below:

https://admissions.cmcvellore.ac.in/process.aspx