Hi Amit 

As you told ,your SC category rank is 556 ,you can easily get AIIMS New Delhi if we go through the last year cutoff ,that is, In 2018 cutoff rank was AIR 1081.

Other AIIMS branches too ,you can easliy apply for like ,if we consider last year's cutoff -

1)AIIMS bhopal cutoff rank-8657

2)AIIMS patna -14195

3)AIIMS jodhpur-5704

4)AIIMS rishikesh -10471

5)AIIMS raipur-13607

6) AIIMS bhubaneshwar- 9083

7)AIIMS nagpur -13638

8)AIIMS Guntur-14510

I hope this information proves helpful to you

All the best