Hello Arvind,

As per the eligibility to apply for UPSC Assistant Commanded, You must hold a Bachelor’s degree of a University incorporated by an Act of the Central or State Legislature in India or other educational institutions established by an Act of Parliament or declared to be deemed as a University.

Officially there is nothing about NIOS candidates. You can also check the complete information with the given below link.

https://upsc.gov.in/sites/default/files/Notification-CAPF-2018-Engl.pdf

Good Luck!