Hey Tamanna, Pondicherry is a fantastic place to ring in the new year. The weather in December is ideal for a beach holiday. I would suggest that you rent a beautiful Airbnb overlooking the ocean and say hello to 2020 with that beautiful view. If you'd like to party it up, there are a number of clubs and pubs that you can head to: Le Club, Toxic, Kofi Bar and L'Aqua. You can refer to this article for more info: https://www.tripoto.com/trip/here-s-why-you-should-ditch-goa-and-visit-pondicherry-5973699a562ed
Book off a good French style villa , you will find many near french colony. Places in Pondicherry are in close proximity , so wont be a problem. Do Visit Mahabalipuram , drive in ECR is Heaven