Traveler visiting US...After the lockdown and shutdown of borders due to corona virus, airports were closed and flights cancelled.What now?

Assuming your aunt is an adult and a citizen of a specific country, she should approach the Consulate of her country's Embassy and also speak to the airline.

But NOBODY knows when we'll be able to fly freely again.

PS: I get that you're probably trolling. But there may be people who really have no clue what to do. Of course they shouldn't ever be let out alone ... but that's a separate issue.

This sounds as true as the fact that the moon is made of green cheese.

Well, I hope your aunt can swim.  Flights are extremely limited but there are flights. Maybe do some research instead of listening to your aunt. 

The airports ARE NOT CLOSED. The borders are not SHUT. SOME flights may be cancelled, but not all. China is just under $3000 from JFK next week. If Mumsy is Chinese, you can send her away for 3K. "Another country" leaves us with 184 ???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? question marks. 184, count 'em! Is it a secret destination? The UNUSED ticket may be changeable to a different date for no charge. ASK THE AIRLINE!

She should speak to the consulate of her country to investigate repatriation flights

And why didn't your mother not make other arrangements or fly out before flights were cut?  Why wait a month later and complain about it?

If she truly can't return home, and I seriously doubt that, than she just has to suck it up and accept the piss poor decision she made to stay

The U.S. didn't shut down outbound borders. You might want to specify what country she's trying to get back to because it may be willing to immediately accept a citizen returning.