My in-laws have been hit by this twice and my parents a couple of times. Unfortunately my in-laws are a bit too trusting.
This seems to be a popular scam, and I’ve listened to the instructions given by the scammer. Their script, if you don’t have the technical knowledge will really make you think that your computer is compromised.
BOTTOM LINE: Microsoft will never call you about your PC. Be careful out there, the scammers are quite aggressive. Keep them on the phone long enough, and they will reveal their very aggressive tactics.
Microsoft didn't call her; she called the number on the ransomware display. She believes it IS Microsoft. I tried to explain it to her, but gave up. To remain married 43 years you pick your battles.