Hi,
Please use the script for monitoring the "gpsvc" service (Group policy client) when the service is stopped alert will be generated and service is started.
Note: Please run the below script as custom monitoring for the expected result.
Refer the below wiki topic that tells how to run it as a custom monitoring script.
https://wiki.comodo.com/frontend/web/topic/how-to-use-custom-script-procedure-monitoring