I came for intership (summer batch) but now from last few weeks I am physically and mentally exhausted, and i may not be able to complete my IT. So is there any other option

The answer to this question can vary from person to person but still i will try to give you one perception. First of all you need to check that how much time is remaining to complete that internship, if it is less than a month then give it a try to finish that. If you leave the internship in  middle without any genuine reason then the organization will see this as absconding and this word is not good for your image because when you will apply for a job in future. Most of the organization will verify your details and if they know about this then it will create bad impression on your personality. There is one more option from which you can easily get out from this situation which is that inform your management with a solid answer that why you can't complete this internship and convince them. But whenever you will start your job or anything in life it will be exhausting in start but fruitful at the end. So take your decisions wisely. Good luck.