Group by

I want to change the following query so that a Sub_Id will be counted in a particular category ONLY if it is the last Sub_ID entered during the given time period. I believe I need a Select Top and/or Group by DESC subquery, but I'm unfamiliar.

SELECT
'Misc Calls' AS Heading,
CASE Sub_Id
WHEN 202142 THEN 'Incomplete Info'
WHEN 202373 THEN 'General Info'
WHEN 201933 THEN 'Workshop'
WHEN 202366 THEN 'No Longer Interested'
WHEN 202367 THEN 'Unable to Reach'
END AS Category,
COUNT(DISTINCT c.Business_Id) AS CategoryCount
FROM
Contacts c
INNER JOIN Businesses b ON b.Business_Id = c.Business_Id
WHERE
YEAR(b.OpenedDate) = 2007 AND
MONTH(b.OpenedDate) = 1 AND
(Sub_Id = 202142 OR Sub_Id = 202373 OR Sub_Id = 201933 OR Sub_Id = 202366 OR Sub_Id =202367)