For the course of MBBS one need to qualify the NEET UG examination. The eligibility for the examination is stated below:

The eligibility criteria for NEET is provided below:

1. The candidate is required to pass the 10+2 examinations & must have English as one of the subject followed by Physics. Chemistry & Biology.
2. To be eligible for NEET, the student need to secure the undermentioned marks in aggregate for PCB:

• UR - 50%,

• OBC/SC/ST - 40%,

• PWD - 45%

Thus you can't take admission to MBBS as you need to qualify the 10+2 mandatorily with PCB. SO you can give your boards through Open school and after qualifying you can appear for NEET & can get admitted in MBBS.

In order to know more about the NEET eligibility criteria you can consider the link below:

https://medicine.careers360.com/articles/neet-eligibility-criteria

For more information regarding NIOS you can consider the link below:

https://school.careers360.com/exams/nios-class-12

I hope this helps. Wish you a great eve!