I am interested in zoology and social service too. Which career options would be better for me?

You can join civil services, as after joining civil services, you will be able to do people's help you will get to know about their problem. You can complete your degree with zoology and then prepare for civil service. Good luck.

You can help people while doing any branch. Just go with the branch in which you are most interested. One more thing while selecting branch, listen to your brain. Helping needs good heart not a good brain while study need a good brain.