If you have only one month left for your campus placements, then I would suggest you to definitely go with Python as since it is a very easy programming language and you will be able to pick it up very quickly.

Once you thing that you have got the hang of Python, then you should start preparing Data Structures and Algorithms as this is the most asked in CS related interviews. You should use Leetcode and Hackerrank to prepare for DS and Algo questions. Once you are done with these things, you are fully good to go.

Hope I have answered your question. All the best!