Pete:

My company has sent quite a few employees over to India in the past few years. Despite having all the suggested immunizations a couple of them have gotten quite ill. In both cases the cause could be traced back to bad water in either its natural state or as an ingredient in cooking.

If your sister will be staying in a well established hotel (such as a Hilton) she should be fine. The water there will be filtered or bottled. If she is not, however, I would strongly suggest an actual water filter (MSR, PUR, etc.) and water containers (such as Nalgene).

You may also wish to include a good supply of over the counter medications such as pain relievers and antacids. I understand from our Indian co-workers that such things can be hard to get in some areas.

I would also give her a small, led flashlight to clip to her pack or clothing. I got my parents a pair of Photon II's for their trip to the UK and they love them. A very small compass with a keyring attachment might be an asset as well if she knows how to use it.

I think the trick here is not to push the items as a "Survival Kit" but more as "I saw this in a shop and thought it would be useful to you".

Chris