verbally told she 'passed' probation - then terminated

My wife was nearing the end of 6-month probation period for a good job she enjoyed, working for a California county. Everything was great with her supervisor and with her supervisor's boss. The first of two scheduled employee evaluations said my wife was "exceeding" expectations. A second scheduled evaluation never happened. During most of the six months, my wife was told she had nothing to worry about as far as passing probation.

Nearing month six, both the supervisor and boss separately congratulated her on having "passed" probation and the boss indicated he would sign the document (he probably never did, but would probably tell the truth).

Then, in the last couple of weeks of the probation period, something went sour with my wife's immediate supervisor, who began claiming my wife was "hostile."
One week before the end of the probation period, they terminated my wife and declined to give an explanation. This was presumably the decision of the supervisor, supported reluctantly by the boss.

Did being verbally told she had passed probation (which the boss will probably confirm if necessary) mean my wife had "de facto" passed probation? Did it give her rights as an employee? Did the failure of the employer to give her a second evaluation create an issue? It would be a very real hardship for her to let this good job go. Thanks. Any guidance appreciated.
Consultation is possible.