The official mascot of the Khelo India Youth Games 2020 was Vijaya. The mascot represents the spirit of youth and sportsmanship.

Option 1 - Vijaya: This is the correct answer. Vijaya was the official mascot of the Khelo India Youth Games 2020.

Option 2 - Jaya: This option is not the correct answer. Jaya is not the official mascot of the Khelo India Youth Games 2020.

Option 3 - Rongmon: This option is not the correct answer. Rongmon is not the official mascot of the Khelo India Youth Games 2020.

Option 4 - Ammu: This option is not the correct answer. Ammu is not the official mascot of the Khelo India Youth Games 2020.

In conclusion, the correct answer is option 1, Vijaya, as it was the official mascot of the Khelo India Youth Games 2020.