There are three options to trigger Rules and apply Actions using Automation 'On Creation', 'On Edit' and 'On all Tasks Completed'.
Fig 1 - Trigger Options
The 'On Tasks completed' trigger will apply your rule when all the Tasks you have created for a Contract or Party have been marked as 'Complete'.
A notification email will be sent to Recipient(s) informing them that all Tasks assigned to either the Contract or Party record have all been marked as 'Complete'.
So your Rule could be:
'On all Tasks Completed' for a <Contract>, create a <Notification> to <Judy Weeks>.
If you do not add any Criteria to your Rule then it will apply to all of your Entity records, if you wish the Rules to apply in certain circumstances then you must specify when the rule should apply using the Criteria.