。
She hasn't come here yet.
Literal
She [topic-は] yet here [to-へ] not-coming.
へ marks direction or destination — broader and slightly more abstract than に, which would pinpoint the arrival location. With verbs of motion the two are often interchangeable, but へ leans toward 'in the direction of' while に leans toward 'into / at.' まだ paired with the polite resultative ~ていません ('has not come and is still not here') is the standard way to report an ongoing absence.