Advice needed rishikesh to goa

Hi have spent a mth india and am trying to adjust my plans accordingly I am currently in amirstar and planned to travel further north both don't feel confident do that alone so have decided to go to shilmla -manali- rishikesh- varansi then to goa but I need to be in chennai for the 14th of dec does anyone have any idea of whether I can get a flight from rishikesh or possibly Varanasi to goa or somewhere south. The bus journeys thus far have been draining . Thank u all in advance i also plan to spend quite some time in rishikesh doing a yoga course any recommendations? My plans are a bit hazy so if anyone thinks Tamil Mary or Kerala maybe better pls do let me know I have nov to jan with only the Christmas period covered x x