M.Com

Hi Aqsa,
The final year candidates are allowed to appear in UGC NET examination. However, they need to have their final year mark sheet at the time of getting the NET Certificate. The minimum eligibility for UGC NET Exam is post graduation degree and the candidates can apply in their post-graduation subject or its related subject.
Check the complete information from the official website before filling the application. All the best.

Generally, M.Com is offered in many colleges but the best ones will always be the best ones. I believe a college is best not by it's name but by the teachers. So here I'm attaching the link address of all the colleges which provide M.Com in Mumbai.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.shiksha.com/accounting-commerce/ranking/top-commerce-colleges-in-Mumbai-all/97-2-0-10224-0&ved=2ahUKEwiDhY2217zbAhXDtY8KHbtZDEQQFjACegQICBAB&usg=AOvVaw1KtspxDsb01c-K55gNYt5s
Hope this helps you.

Yes, she can get admission there.
Refer the link for details: https://www.shiksha.com/accounting-commerce/course/m-com-shri-ram-college-of-commerce-maurice-nagar-delhi-53148

Yes, you can. If you clear the exam, then it definitely makes you eligible for the course for which you have given the exam.

The course of B.Com, plus, all the basis of the subject you wish to do M.Com in, must on be your tips.

Check the syllabus at http://puchd.ac.in/syllabus.php.