I am about to submit my form for m.a in dm university imphal.is it ok if I submit with my tribe certificate of 2018 will it be acceptable
Yes
The caste certificate is issued mostly once , it is re-issued only in the case of loss or theft.
So surely your certificate is valid and it will be accepted.
But if the college have given any criteria of selection of certificate then it must be taken in view , like the income certificate must not be more than 2-3 months old.
All the best!!