To answer this question, we need to have an understanding of the story of Ramayana.
In the Ramayana, Sita was kidnapped by the demon king Ravana and taken to his kingdom of Lanka. After Rama, Lakshmana, and Hanuman traveled to Lanka and defeated Ravana, they prepared to return to Ayodhya.
During their time in Lanka, Sita was held captive in Ashoka Vatika. It was here that Ravana's wife, Mandodari, gave Sita a beautiful gem as a gift. Sita, being a devoted wife to Rama, decided to send the gem back to him as a token of her love.
The gem was presented to Sita by Mandodari, who was Ravana's wife, not by any of the options mentioned in the question. Therefore, none of the given options are correct.
Hence, the correct answer to the question is not provided in the options given.