I believe in NYC the landlords are responsible for exterminating the bedbugs. (As unfair as it may be to landlords).
Bedbug treatment can be successful, albeit expensive, but only if the occupants are cooperative. And sometimes multiple units are infested so they must all be treated simultaneously to avoid reinfestation. The sooner it’s treated, the better as these bugs unfortunately do multiply. And believe it or not cleanliness is not really a factor, it’s more a matter of bad luck. (Although “clean” sensibilities come into play with how seriously it’s handled after becoming aware that one has them.)
My best advice would be to try to set up a fund and tackle these issues one by one as money is the answer to most of it…