You must file I-290B within 30 calendar days from the date USCIS issued the denial notice (11/29.2023).
Because it is close to Christmas holiday, the mail service is very busy and USCIS may take holiday break. So, you need to file I-290B as soon as you can and may use Express mail such as FedEx Express, UPS Express to send the I-290B filing packet to ensure USCIS receive it before December 29.
By the way, because your mother's I-485 was denied, her advance parole was also invalid. So, if she has trouble to reenter US at the port of entry, just explain to the immigrant officer that she did not know her I-485 was denied before she travelled out of US, so she needs to reenter US to file an appeal for the I-485 denial.
