Elphaba is shocked and happy. Nanny spills Elphaba's name, so now everyone knows it. But she still gets called Auntie Guest/Witch, since old habits are hard to break.
Nanny says she learned that Elphaba was a nun through Crope, who knew that Elphaba tended Tibbett on his deathbed. So Nanny decided to track Elphaba down.
She also reports that the Wizard has crowned himself Emperor.
The Wizard is just like Napoleon, who (in)famously crowned himself emperor of France, and a bunch of other places that he'd taken over, in 1804. He literally took the crown out of the Pope's hands and stuck it on his own head. Good stuff.
Elphaba is appalled and climbs back up on her political soapbox.
Nanny then makes Sarima and the Sisters angry by calling them all collectively "old and female."