1. I have passed +2 with Diploma in Co-Operation. Am i eligible to apply this post?
For this post, education qualification is any degree with diploma in co-operation. So you are not eligible to apply this post.
2. I am studying Diploma in Co-Operation at present(2019-2020). Am i eligible to apply for this post?
Yes. You are eligible even if the course (Diploma in Co-Operation) is ongoing.