Dittoing what BLUTANG said regarding recs and a waiting period-- TBS and KKPsi are not like the social organizations and do not conform to their rules of rush and such. Individual campuses may be different, however, in their guidelines of letting any student into any organization, so she may want to double-check with the student activites/organizations office just to double check.
My suggestion would be to look into pursuing membership again when her grades are more stable-- it's very possible that she will get in. She may wish to talk to the active brothers, too, and get to know them.
And if she's not fitting in with KKPsi, there is a strong TBS chapter there as well.
Best,
Mel.