My father (1)/ has returned back (2)/ to Chennai yesterday. (3)/ No error (4)

Answer

2

Explanation

back will not be used with returned because- returned (Verb) means come/go back. Look at the examples given below:
Are you planningto return to India? In spoken English, we use go/come back Areyou planning to comeback to India? Hence, has returned Is the right usage