There are a variety of ways to do this in Tableau, the point and click way is to:
1. In the Dimensions window ctrlclick (cmdclick on Mac) on the Drg ID and Provider ID fields in the Dimensions and then right-click and choose Create->Combined Field. Tableau will create a new field that is the combined field.
2. Drag the combined field to the Filters Shelf.
3. Click on the Condition tab.
4. Click on the By field button and add a condition for Financial Year/Count (Distinct) = 4.
5. Click OK.
What this does is add a filter that only accepts DRG/Provider combinations that have all 4 financial years in the data.
Thanks a lot, that worked!! This would get me start my analysis