It being at an apartment complex you would think the apartment complex should deal with it and not make her spend money on it.... with that being said, My wife's old house in Mt Gilead, we had an issue with fleas and it seemed like no matter what we did, we couldn't get rid of them... they were outside, inside, they were everywhere.... Then one of her friends recommended this stuff called diatomus earth... it is non-toxic and you can eat it.... but we put it all around the paremeter of the house and then all over the carpet, let it sit for a few days on the carpet, then vaccumed.... we never saw another flea again.... I guess the way that stuff works is it gets in their exoskeleton, and then causes friction as they move and pretty much burns them alive.... but it also carries it back to the coloney so it kills all of them.
That might be a cheap non-toxic alternative since she can't bomb her apartment.