Surely the urologist that diagnosed her in the Emergency room noted that she see him/her on a follow-up appointment. Then the check-up will determine if the stone was passed. Patience is required. If she has no pain at this time, more than likely the stone has been passed.
My wife gets lots of anxiety and for a few years when we were first married she would get some pain in the middle of the night, get anxious about it, start to panic and think she was dying or something. She'd insist on going to the emergency room.
From this process I learned a couple of things. First, in the middle of the night the ER doctor's job is to keep you alive until 8am when the regular staff comes in. If you aren't dying, they won't talk to you more than once, maybe twice if you're lucky. Second, you never see them again once you leave. That's not their bag.
I finally told my wife "These ER doctors in the middle of the night will do nothing for you unless you are in cardiac arrest. If you seriously think you can't make it til morning, then we'll go. Otherwise I think you're better off waiting and seeing a doctor in office because that's what ends up happening anyway". She agreed and we haven't gone back to the ER in 10 years.