Does a two-year gap after graduation hinder admission to a top B-school (IIM, XLRI and FMS)?

You do not have to worry about that because not only my elder brother, but a number of other seniors and alumni of these Institutes had gap years. They were building a startup, or preparing for Civil Services, or even trying new skills. Let us check the selection process of these top business schools -

• The selection criteria are based on two levels- the first is by compiling the marks of 10+2, graduation, and CAT. 
• The work experience is turned into a score too, along with professional certificates, higher education, academic and gender diversity.
• IIMs in particular follow this criterion and give the CAT exam a very high weightage.
• You can strengthen your profile by building skills or working on projects or a startup.
• The final step includes the WAT(Written Ability Test) and PI (Personal Interview). 

The scores of these are combined and finally, during the interview, you will be asked about your gap years. 

It is up to you how you can connect your gap story with your future goals. The MBA program is full of talented aspirants and the panelists select only those who can utilize the subject wisely and make it work for their goals. Gap years will be considered advantageous to your profile if something unique comes out of it.