Just to confirm..
Is it possible to use a workflow 2013 to Assign a Task to a SharePoint 2013 Group?
Is it possible to email a SharePoint 2013 Group from Workflow 2013?
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Maybe creating AD group and than instead of a username you put AD group name. That is how we did this for alerts and some other notifications.
and answer to your question is yes, you can send an email to group. here is a topic about it: Definitive answer to sending emails to SP Group from Workflow