You need to create a template custom:
mkdir -p /etc/e-smith/templates-custom/etc/samba/smb.conf/
cp /etc/e-smith/templates/etc/samba/smb.conf/30audit /etc/e-smith/templates-custom/etc/samba/smb.conf/
Then tweak /etc/e-smith/templates-custom/etc/samba/smb.conf/30audit to your needs. Finally: signal-event nethserver-samba-save
Regarding the AV, please consider that is not supported on NS so you need to find a good balance between auditing and antivirus 