is nios is eligible for mbbs ..
If you are asking if Nios students are elligible for NEET then yes.
From NEET 2021, now NIOS students can also appear for NEET. The decision is taken by MCI as till last year it was not allowed for NIOS students to appear for NEET.
Admission to MBBS in India and universities abroad is done only through Neet. So the first NIOS candidates must run for Neet. NIOS students are eligible for NEET as long as they are at least 17 years old as of December 31 of the exam year and obtain the required minimum aggregate against their Category, which is 50% for general in PCB, 45% for PwD and 40% for SC. ST, OBC. If you meet Neet's eligibility criteria, you can apply for Neet, and based on Neet's score, you can get admission.
Please see this link for detailed eligibility criteria :
https://medicine.careers360.com/articles/neet-eligibility-criteria
I hope this answer helps. All the very best for your future endeavors!