Is the alternator warning light still on when the engine is running ?
If it is then it sounds like the fan belt has snapped
On most cars the fan belt goes around the alternator and the power steering pump therefore if the belt has snapped then the power steering wont work and the alternator wont charge neither, thats why the warning light is on the dashboard, its a Low Charge
If this is the case then its not advised she drives the car far as the alternator isnt charging the battery therefore the battery will drain very fast due to lights & Wipers pulling lots of current.
The Power Steering cap is normally black and about the size of the top of a coffee jar with a serated edge to it for grip. Normally located at the front of the engine bay, possibly by the battery.
Let me know how you get on matey.....