the HEAT treatment is not required, landlord can opt for pesticide which is cheaper.
state laws vary, in some states, the landlord is always required to treat at his expense. in others, if she can prove the tenant was negligent or brought in the problem, the tenant is liable.
NOTE: YOU AND YOUR MOTHER FAILING TO REPORT IT RIGHT AWAY IS NEGLIGENT. you previously said the sheets were so badly stained with blood they had to be thrown away....that indicates you let the problem go on for a long time...and could even be held liable if they spread to other apartments
she can stay in the home for the pesticide (just move to the room not being treated at the moment, or can just wait outside for a short time.
she WILL NEED TO LEAVE FOR HOURS FOR THE HEAT TREATMENT.
if it can be shown you/your mom/your guest brought it in, you can be held liable in some states. and yes there is a chance a person who rarely goes out could have brought them in...such as from the waiting room in a doctors office.
in some states, the tenant is financially responsible no matter what.
if the care provider works in other homes, that is a high risk. i heard of a case where the agency who provided the aid was successfully sued (it was a live in whose own house was infested).
bed bugs have been found in movie theaters and schools...could have gotten into bros locker/book bag.
not only does your apartment need to be treated, surrounding apartments, possibly the whole building needs treatment.
what do you mean she has housing? everyone with a roof over their head has housing. do you mean some type of low income housing? since you live there is your income counted? what are you contributing financially?
you can pay the bill, and don't insist on the more expensive treatment when it happens again (because the other apartments weren't treated)
but then again, if it was as bad as you say (due to your negligence) heat may be cheaper as it is more efficient, may have needed NUMEROUS pesticide treatment...and you would have to follow through with your part cleaning everything...