What is the easiest way to show who from a particular data extension has unsubscribed from All Subscribers?
If you mean to check all the subscribers you have in a particular DE that contains their SubscriberKey, you can write a query to join these records on the _Subscribers data view to determine their subscription status in All Subscribers.
You don't unsubscribe from a Data Extension.
You unsubscribe from a All Subscribers, a List or a Publication as defined in your Send Definition.
SFMC will automatically keeps track of subscriber status via Subscriber Key in those three places, nowhere else.
You can have some field that represents status in your DE, but you'll have to build something to update it.