Okay!, here we go.

Download  check_yum plugin from https://github.com/calestyo/check_yum/blob/master/check_yum to /usr/lib64/nagios/plugins/ on your CentOS nrpe server.

Add the command on your nagios.cfg

command[check_yum]=/usr/lib64/nagios/plugins/check_yum

Restart NRPE

/bin/systemctl restart  nrpe.service

And on your nagios server on your host/s5.domain.com.cfg

define service {
    use                    generic-service
    host_name              s5.domain.com
    service_description    SYS: system updates
    check_command          check_nrpe!check_yum!1
}

Restart Nagios

/bin/systemctl restart  nagios.service