Hari OM! Please comment below if you have suggestions in addition to the following:

Paperwork:
Photocopies of your passport and visa page
Passport size photos of yourself (at least 5)
Copy of all credit cards and documents
ATM cards (ATMs are everywhere). Call your bank first and tell them you are going to India!

Clothing:
Clothes shopping in India is of course awesome, and we will have time and assistance specifically for that. We will be mostly in villages, rural areas and places of worship where modest clothing is appropriate. For ladies it is considered inappropriate to show legs and shoulders.

Footwear:
Sandals comfortable for walking, but not fancy enough to make strangers want to borrow and not return them. Closed shoes can be a pain because you will have to take them on and off frequently when going into temples, homes, and even stores.

Drug Store (Chemist)
Priobiotics
Feminine products
Sunscreen
Emergen-C packets and vitamin C
Liquid multipurpose soap like Dr. Bronners for washing clothes etc.
Mosquito repellant
Ibuprofen
Sunglasses
Antiseptic cream (Neosporin)
Tea Tree oil
Earplugs
Hand sanitizer (also available in India)
Kaopectate or Pepto-bismol tablets
Band Aids (plasters)
Zip-Lock bags
Immune boosting supplements/vitamins

Travel goods:
Favorite dry goods/snacks/bars etc.
Warm socks or slippers for indoor marble surfaces that can be cold
Outlet converter for powering electronic devices
A daypack or shoulder bag
Sleeping Sack / warm weather sleeping bag liner
Headlamp/flashlight/torch for night adventures and power outages
Combination lock for luggage and hotel door rooms
Water bottle
Yoga Mat/Props