how should i prepare for physics in this last time for aiims

Concentrate on NCERT most. 2016 AIIMS had most questions in bio section from NCERT itself. For physics fluency in problem solving is a must as questions tend to be really conceptual.
Another aspect to be taken care of is Assertion Reason type questions. These require critical thinking...and a good grasp of the topics.
GK is usually a low scoring section and i found some questions to be quite hard.
The difficulty level of the AIIMS paper was very high especially when compared to other entrance exams (medical) like AIPMT, CMC, manipal, JIPMER etc... 
All in all, if you work really hard, master concepts,and solve mock tests regularly that are of AIIMS pattern, you will surely get a good rank in AIIMS entrance exam
all the best !!!