Unless she was removed by court order before she was age 18, until she is age 24, has an dependent, is married or a veteran, for financial aid purposes she is a dependent. What she should do is spend some time with the mother and get her financial information for year 2012 to use for FAFSA. The less means the mother has, the better since that just might get her a big fat zero for Expected Family Contribution which means about $5550 in PELL grant. The young lady would also qualify for $5550 in her own name in direct loans, and if her mother owes money from here to tomorrow with her credit shot, she can apply quicky for a Parent loan and upon getting denied, the daughter would be eligible for $4K more in loans. Also if the state has any programs for low income families, the daughter may qualify for them, such as TAP in NY.
That gives her some alternatives in terms of continuing to live with SIs and commuting to a local state school. If her grades and test scores are up there, some local schools might also throw in some merit awards to make it just as easy or even less to go to such schools.
However, if the young lady is eying some schools where she want to board, getting the aid necessary will be trickier and truly a lottery ticket, her chances depending on the schools and her test scores/grades.
Those schools that also require a CSS PROFILE and those tend to be privates that tend to give more generous aid packages over all will ask for both parents' financial information and are highly unlikely to care that the dad lives in antoerh stae with a new wife and 2 kids and will not be making a contribution towards her college costs. In fact they'll want to know what that wife has and makes as well as those two kids--yeah, I'm not kidding, and include that as sources. They may also want to know what the sister contributed in towards the student in the prior year and certainly will ask what she will be contributing. They say EFC for FAFSA stands for "Every Friggin' Cent" but that's before you file a PROFILE. They go after the gold in the teeth.
So a lot of this depends on what the young woman is considering in types of schools, and she may have to reconsider after absorbing this info. But if she is a top student who is a contender for entry at HPY, for example, it may be worhtwhile trying to get dad's info and seeing what falls out or filing a NCP Waiver form. If she is looking at local options, that is a whole other story.