Hey 

the cut off varies every year depending upon the difficulty of the question paper

the cut off for SC category is 40% & hene you will need a score of 60-100 to secure a seat in any AIIMS out of 200. 

For delhi AIIMS you might need a score above 100 but this is a very rough estimate.

you having SC quota gives you an advantage as with a lesser score too you can get a good college 

you can check out previous years cut off & marks list on career 360 to get a more solid idea. 

work for it & get it

good luck!