Option 1 states that the Government of India followed the calendar based on the Saka era at the time of independence. The Saka era is a historical calendar era commonly used in India, and it begins with the Saka king`s ascension to the throne. However, there is no direct mention of the Government of India following the Saka era as the calendar system at the time of independence. Therefore, option 1 is incorrect.

Option 2 states that the National Calendar commenced on Chaitra I Saka, 1879, which corresponds to March 22, 1957 AD. This means that the National Calendar was adopted based on the Saka era in 1957. This statement is correct.

As option 1 is incorrect and option 2 is correct, the correct answer is option 2 - "2 only."

Therefore, the Government of India did not follow the calendar based on the Saka era at the time of independence, but it did adopt the National Calendar based on the Saka era in 1957.