With the current situation of the virus, traveling anywhere sounds like a very risky operation, especially for elders.That is the main reason behind this question.
However, there’s no easy way to extend status,
She likely won't be allowed to go home at this point in time. The news has been showing reports about a repatriation flights from USA are being refused from many countries –
With the current situation of the virus, traveling anywhere sounds like a very risky operation, especially for elders. That is the main reason behind this question. If US government will allow visitors to overstay until Covid-19 settles down. –
More seriously, there could be some sort of amnesty or other program offered to nonimmigrants in the US who are affected by the pandemic. If that happens, it could save you a few hundred dollars.
But I wouldn't count on it. I certainly haven't heard any mention of it, and the current administration sounds profoundly anti-immigrant, so it's unlikely to happen without political pressure.
In terms of risk analysis, the application fee will be well spent.
If so, is it possible to waive the fee due to the Corona virus situation?
Applying for a fee waiver is going to make her look like someone with financial problems, which will have a negative impact on her application as well as future applications for admission to the US. I would not do it.
Once the application is filed, she can remain until it is refused, or, if it is granted, until the end of the period of extended stay that is granted.
I think the next step after application is to come in for a "biometrics" appointment. However, for good reason (virus), USCIS has recently decided to close all "biometrics" centers. I suspect this will have a positive effect on application. It will just be on hold until they can schedule a biometrics appointment. However, who knows what they will do.
"she can legally remain until it is refused or as long as approved" -
If denied, it will indicate the grace period, not that it is specifically or always 2 weeks. I would recommend 6 months at the minimum.