The correct answer is option 2 - Cardamom hills.

To understand why, let`s analyze each option:

1. Anaimalai hills: These hills are located in the Western Ghats of Tamil Nadu and Kerala, but they are not the southernmost hills. They are situated more towards the central part of the Western Ghats.

2. Cardamom hills: These hills are located in the southern part of the Western Ghats, spanning across the states of Kerala and Tamil Nadu. They are the southernmost hills among the given options.

3. Nilgiri hills: These hills are also situated in the Western Ghats, primarily in the states of Tamil Nadu and Kerala. However, they are located slightly north of the Cardamom hills. So, they are not the southernmost hills.

4. Javadi hills: These hills are located in the eastern part of Tamil Nadu, near the city of Vellore. They are not part of the Western Ghats and are located considerably eastward from the other mentioned hills. Therefore, they are not the southernmost hills either.

In conclusion, among the given options, the Cardamom hills are the southernmost hills in India.