I-539 filed and I-797 approval given but have questions
Earlier this year my father (non-res alien B1B2 visa) became ill and passed while at his home on FL. My mother (non-res alien B1B2 visa) was forced to stay past her 180days and filled an extension (I-539) before her status expired. She would have extended her stay if she stayed in the US past April7th but filed the extension before that date; she was able to leave the US on June 26th and she has not returned since. She has just received an email stating that her extension request has been approved and that an I-797 form has been mailed to her US address and to follow any instructions therein.
Unfortunately Mum has a flight booked to return to the US on Jan 5th, this does not allow time to received the I-797 form nor read its instructions.
Should my mother be worried about trying to re-enter the US? Any guidance would be greatly appreciated as she is quite worried about trying to re-enter.