You scared me. It is now still OK for parents to stay if the extension
application is pending but the I-94 is expired. Please read and understand
what is said below from the official website.
What if I file for an extension of stay on time but USCIS
doesn't make a decision before my I–94 expires?
Your lawful nonimmigrant status ends, and you are out of status,
when your Form I-94 expires, even if you have timely applied
to extend your nonimmigrant status. Generally, as a matter of
discretion, USCIS will defer any removal proceedings until after
the petition is adjudicated and USCIS decides your extension of
nonimmigrant status request. Nevertheless, DHS may bring a
removal proceeding against you, even if you have an application for
extension of status pending.
Even though you are not actually in a lawful nonimmigrant status,
you do not accrue “unlawful presence” for purposes of inadmissibility
under section 212(a)(9)(B) of the Act, while your extension of
status application is pending if it was filed prior to the expiration of
your Form I-94.
Although you are out of status, you may be permitted, depending
on your classification, to continue your previously authorized
employment for a maximum period of 240 days while your extension
application is pending if USCIS receives your application before
your Form I-94 expires, and you have not violated the terms of
your nonimmigrant status. You may be required to stop working,
immediately, when the first of the following events occurs:
• 240 days elapses from the date your I-94 expires; or
• USCIS has made a final decision denying your extension
application.
If your application for an extension of stay is approved, the approval
will relate back to the date your Form I-94 expired, and your status
during the pendency of your application will then be considered to
have been lawful.
If your application is denied, you may be required to cease
employment and depart the United States immediately.
In addition, any nonimmigrant visa in your passport granted in
connection with your classification becomes void. Once your visa is
void, you must submit any new visa application at a U.S. consulate
in your home country (not a third country, except in rare instances
as determined by the U.S. Department of State).