Its hard to say the marks needed for admission to AIIMS Delhi. Percentile is a more stable and better predictor. For Delhi you need to score above 99 percentile which corresponds to a rank below 300 and OBC rank below 20. 

How far as i remember, in 2016, when i took admission to AIIMS, the minimum was 130 i guess, although that time seats were not 100, but 72. A score of 140+ is safe, although it varies highly depending on shift of exam and exam question level.