You cant close the deposit. It will be held as a perpetually auto renewed deposit without ability for closure till you hold the credit card.
Hostel fee is not income. Do you understand what the words "in come" mean? You didn't year what that sales man said correctly or he is not a sales man at all.
Stipend is income, but there is simply not enough of it for an average student to even consider it as qualification for a credit card. For example, during my M.Tech course which was through GATE qualification, I used to get a stipend of 60,000/year. Nowhere near enough to qualify for credit card as most banks require 1.5-2.0 lac minimum income.
Rent income could qualify if there is sufficient amount of it, you receive it via a source like bank transfer and and you are paying taxes on it. Otherwise, its simply not even visible as income to them.
Simply put, what banks are looking for is that there must be some activity visible against your PAN number that they can deem as stable income.