。
She hasn't come here yet.
Literal
She [topic-は] yet here [at-に] not-coming.
The に here pinpoints 'here' as a location of arrival — slightly more concrete than the parallel form with へ, which leans toward 'in this direction.' The pattern まだ + ~ていない reports the state of not-having-arrived as ongoing, distinct from a simple 来ない (still doesn't come / isn't coming).