I am trying to understand if there is any real time scenario when we will need to call future method from batch class ?
Can anyone please help me ?
No, there's no scenario where you would call a future method in a batchable method. This is because the system does not allow you to do so. If, for some reason, you need another asynchronous call, you must use Queueable. Note that you are limited to just one Queueable per execute method. This is called out in Execution Governors and Limits. Since you mentioned this is for an interview, it's worth studying this document carefully, since many interviewers will ask questions of this nature regarding governor limits.