Classic case of a worn out clutch. If she continues to drive it that way,
it could leave her stranded. Plan on replacing the clutch disc, pressure
plate, throw out bearing, pilot bearing, and you may be wise to have the
flywheel turned by a machine shop. The last item is dependent on flywheel
wear or heat caused by clutch slippage. Bad things start happening when
driving with a worn out clutch.
Good luck.