I am wanting to transfer a subscription to Google Home from myself to my ex-wife's email. Is this possible or does she need to just pay for a new subscription and add the cameras? I would prefer to transfer if possible as the account has her mother's cameras on the account as well.
Unfortunately, Google Nest does not have any transfer mechanism. You will have to treat the situation as if you were moving and transferring devices to a new owner. Basically, you will need to remove everyone from your Google Nest "household", remove all the devices from the Google Nest app or Google Home app, and then do a factory reset of each device. You will also need to cancel your Nest Aware subscription and your wife will need to get a new one.