How to use multiple columns in order to get distinct COUNT of records in excel file

Currently I am using below code to find the count of occurrence in excel file for field “Month_Year_TR_Due_Date” which is correct .

filtered_excel_TR_Due_Date_NULL.AsEnumerable.GroupBy(Function(x) x(“Month_Year_TR_Due_Date”).ToString).Select(Function(g) String.Format("{0} - {1} ", g.Key, g.Count())).ToArray

But I have to use one more column in this in order to find count of unique combination for both fields. I tried all available options but it’s not allowing to add another column in this code.

Can someone help.