I-94 Visa Issues Due to Iceland Volcano

My mother-in-law currently has a B2 visa and the I-94 stamp has a date of April 21, 2010. She is scheduled to leave on Monday April 19th. Due to the Iceland Volcano, there is a good chance her flight will be canceled. My question is, what will happen if she can't get a flight until after April 21? She will then be considered "out of status". As of now, her flight is still scheduled. Any help would be great, thanks.

[AFFA]

I wish to inform you that your mother-in-law must submit the I-94 at the time of departure. If due to natural calamity the flight is re-scheduled the transportation carrier can give a note and attach it to the I-94 about the circumstances of delay beyond the hands of the passenger. You can also contact the Customs and Border Protection (Passenger Operations) for guidance.

AFF