Dear Priya,
Answer of this comes from SEBI LODR 2015 Regulation 17A talks about the Number of Directorship and that is:
(1) A person can be director in 8 listed companies from 1 Apr 2019 and from 1 Apr 2020 in 7 companies only.
Provided that a person cannot be an Independent Director in more than 7 Listed entities.
(2) Where a Person becomes a whole time director or managing director in a company the person can further be independent director in only 3 companies.
However as far as unlisted companies are concerned which are completely governed by Companies Act 2013, required to appoint independent director as per section 149(4), one can not become director in more than 10 public companies as per section 165.
Conclusion: As per my Opinion if anyone is independent director in only unlisted companies he may become independent director for 10 Such companies but if he is independent director in listed entities it can only be in 7 such companies.