Is it permissible to slaughter a cow and distribute some of its meat on Eid al-Adha, and deduct the cost of the meat given to the poor from zakat al-mal, given the security conditions that prevent the distribution of cash?

It is permissible to advance Zakat after the completion of the nisab, according to the majority of scholars. If the funds are distributed with the intention of Zakat before the hawl (one year), they will be counted as such if the hawl is completed and the distributed amount covers the obligatory portion. Otherwise, you must complete the deficit. You are not obligated to distribute the money on Eid al-Adha. It is recommended to appoint someone trustworthy, just, and knowledgeable about the masarif (categories of recipients) of Zakat to distribute it on your behalf, especially if you fear showing off or are ignorant of its rulings. As for paying Zakat by slaughtering a cow and distributing its meat on Eid al-Adha, this is a payment in kind and is not permissible unless it serves a benefit and advantage for the poor.