The Marketing List Members view is not customizable by standard CRM methods. The View can be customized using the following method:
In CRM, run Advanced Find.
Set the Look for to Views.
Change the Select to View, Equals
Select All Members in the Lookup field. This will show 3 All Members in your Lookup. One for Account, Contact, or Lead.
Click the Find button and you should see 3 All Members Views, one for Account, Contact, and Lead. Double click on each view to open.
Select the Add Columns button and chose the property you want to add to the view.
Click Save and Close to save the changes.
The changes now need to be Published. In CRM, goto Settings -> Customizations -> Customize Entities.
Click the More Actions menu items and select Publish All Customizations.