Hello

As per the Delhi University's information bulletin, Merit is calculated through course-specific combinations of marks obtained in the qualifying examination in the “Best Four” subjects for admission to courses through the faculties of Arts, Commerce, Mathematical Sciences, Music, Social Sciences, Applied Social Sciences & Humanities.
http://www.du.ac.in/du/uploads/COVID-19/28062020_UG.pdf

Kindly mention that you are seeking admission in which course? So we can help you accordingly.

Also, you can check your admission chances in colleges based on your marks in class 12th using the Delhi University College Predictor Tool.

No you cant add these subjects as your best four if you go for honors of science then you have to take your PCM marks for compete in the admission process.

Best four depends on your choice of course if you choose a course in music then you have a option for taking music as one of the best subject.

ALL THE BEST