Form I-539, Application To Extend/Change Nonimmigrant Status Case Was Denied

[KPC]

Hi,
Due to Covid19 pandemic and considering the health of our parents, we have applied for parents  B2 visitor visa extension i.e., Form I-539, Application To Extend/Change Nonimmigrant Status B2 TEMPORARY VISITOR FOR PLEASURE on April 18,2020. Unfortunately, we did not receive ASC Biometric Appointment Notice original through postal mail. We are unaware and have missed the scheduled appointment on December 02,2020. The biometric appointment appointment was scheduled over the 6 month extension period.
In the meanwhile in November 2020 we have applied for another 6 month extension. And we have received Biometrics appointment for second ext (which was filed in November) and submitted it on Feb 25,2021.

Since we have missed first extension biometric appointment. Our case was closed and denied due to "PSC I-539 No Show for Biometrics Abandonment Denial SCO". And the notice has below mentioned at the end:
Please be aware that, under section 212(a)(9)(B) of the Immigration and Nationality Act (INA), an alien who accrues more than 180 days of unlawful presence in the United States, and then departs, is inadmissible to the United States for a period of either three years or ten years. You may remain in your current nonimmigrant status until the expiration date indicated on your Form I-94, Arrival-Departure Record. However, if the date listed on your Form I-94 has already passed, this Notice of Decision may leave you without lawful immigration status and you may be present in the United States in violation of the law.

Question: 
1. After we receive this letter how long can they stay ? Because their I94 expiration date was May 2020. And we received this notice online few days back.
2. My parents are scheduled for COVID vaccination. Just wondering if they Can they stay for couple of days and leave. Will there be any problem in future?

Thanks 
KPC
 

[newacct]

Officially, they immediately cannot stay anymore. However, they will not start deportation proceedings for 33 days after the date of the denial. If they think the denial is in error, they could try to reopen it; otherwise, they should leave within this 33-day period. The visa that they used to enter the US has been automatically voided. They started accruing "unlawful presence" from the date of the denial, but that won't trigger a ban unless they leave after accruing more than 180 days of unlawful presence. If they are put into deportation proceedings, that may also trigger a ban; that's why they should leave within the 33-day period. It is impossible to predict whether they will have trouble getting a visa in the future.

[JoeF]

If they overstayed the I-94 for more than 180 days they have a 3-year ban. If they overstayed for over a year they have a 10-year ban. All that is triggered by my leaving the country. They should discuss their situation with a good immigration lawyer ASAP.