Any chance in XLI? I have a huge gap of 3 years after my grads with avg acads & will be 4 years till XAT 16 working with an NGO for a year?

You would certainly have to explain to the interview panel the reason for the gap although it should not be a deterrent in your selection. Be honest and don't try to fool the interviewers. You would be affected mostly in the placement process but even there an honest answer should get you through.