We know the real reason why Aaji brought Antara to care for her is so that Raghu and Antara can realise their feelings for eachother.
Aaji knows Raghu really well, she brought him up. She knows that Raghu has feelings for Antara, which is why he is always arguing with her and she knows Raghu will think of Antara and even playe her song in his mouth organ.
And now, she took this opportunity and told Raghu to rectify his mistake. This would initiate Raghu to start feeling whatever is inside of him for Antara.