But 3days ago I got an email that nios candidate is eligible 

Hello Imran.Sorry for the inaccurate information. As per interim orders passed by the Delhi High Court on February 26 and February 28,NIOS candidates are now allowed to fill the NEET 2018 application form. BUT also you are only be allowed to fill and submit the form for now. . The final verdict on whether you will be allowed to appear for NEET  on May 6 will only be determined at the next hearing scheduled for April 16, 2018.For reference, you can check the link below. https://medicine.careers360.com/articles/neet-2018-all-aspirants-can-apply-for-now-rules-delhi-hc