Masters

Yes! It is absolutely possible to change the specialisation even after doing under-graduation from a particular stream. Universities allows but this transition generally degrade your value in the market. Suppose, you have done your under graduation in specialisation in Economics (Say, BA Economics), but now you want to change for Political Science (Say, MA Political Science), university will definitely allows this. Some university ask for particular entrance exam for PG and some may not. But this transition is possible. However, I'd not recommend to change in specialization because due to this change you lacks in "in-depth knowledge (or core knowledge)" of particular subject. Hence it is advisable to continue in your stream. According to me the best combination in UG-PG course is BA-MA in Economics (specially when it comes to Humanities section). The reason that why I am suggesting you this combination is, its market demand and future prospects. Currently, because of the ongoing economic activity in India, the need of economist is exponentially high and it is supposed to increase in near future as well. Hope this helps.
Best of Luck.

It is said that 'credible competition law, and effective structures to administer that law, are necessary for an efficient functioning economy', so is the importance of the competition law. Pursuing additional certificate course and Diploma with mainstream course has been the choice of academicians for following reasons, firstly it gives you more knowledge of the course you interests in. Secondly, it keeps you updated with recent changes and challenges. Also, it enhances your career opportunities. Diploma/certificate in competition law can give you mover advantage in your career.
Course deals primarily with markets and business laws, competition policy and law, in general, and the Competition Act, 2002 . There are institutions which offers you these courses online and offline as well. It's your choice, what you want to pursue.

Pursuing additional certificate course and Diploma with mainstream course has been the choice of academicians for the following reasons, firstly, it gives you more knowledge of the course you interests in. Secondly, it keeps you updated with recent changes and challenges. A study of Principles of Family Law in India is only one of its kinds in the world. In India, Family Law is the personal law of the person, which deals with the matter pertaining to a person and his or her family.
Hindu, Muslim, Christian and Parsi have their different personal law in India. Some of these laws are uncodified while some others are codified. Pursuing additional Diploma in Family Law helps you to understand the basics of marriage, divorce, maintenance, adoption, custody, guardianship, acknowledgement and successions, which in turn helps you a lot in your practice.

Hey There.
An additional qualification is always an addon for your career and enhances your job prospects.
Now having a certificate course or Diploma or an LLM in banking law would grab the attention of law firms as well as the corporate firms and you get a better chance of getting placed.
The additional qualification in banking law is preferred by firms as the person is deemed to have an additional knowledge of Banking Act and the SARFAESI which in recent times have got importance and need special hands to take the matters and thus you would be among the priorities of recruiters.
Also, banking law is something in which not many people opt for a specialisation and thus there is a dearth of candidates.
So, your overall prospects increase and also you are in a better position to attempt those queries related to banking and SARFAESI Act.

I am not sure about physics, but surely you can combine maths with your humanities subject. If you have economics in your humanities subject then maths as an additional subject can definitely prove to be a boom for you. Knowledge of core mathematics is highly necessary for understanding the advance theorems of Marco-Micro economics. When it comes to the understanding the concept of consumers producer behaviours, price determination, revenue recognition, etc., you must have the knowledge of matrices, differentiation & integration, statistics and probability. These concepts help a lot while having an advanced and realistic knowledge of economics (as a part of humanities). So, in this way, we can relate the subjects of maths and economics. Here, physics may not help you much (since physics is the application of mathematics in the practical world), but it may help you to enhance your mathematical calculation skills. Hope this helps.
Best of luck.