Choice (b) is English; e.g., his story didn't just ring true, it also ...; however, it doesn't work here given the transition but somehow:
He claimed to have been at home all evening, but somehow his story just didn't ring true.
(b) didn't just ring true
(c) just didn't ring true
Just modifies the closest word or phrase: just didn't; just ring; just wait; wait just a moment.
Student or Learner