If uniqueidentifier is sequential you can also use subquery like that;

SELECT 
   T1.BoxNum,
   (SELECT TOP 1 T2.Status 
      FROM [Table 2] T2 
         WHERE T2.Table1_FK_ID = T1.Id ORDER BY T2.Id DESC) AS Status
FROM [Table 1] T1

But if there is no related data in second table it could be error, then you need to check data existence.

I am guessing this is simplified example of your data. Basically, you need a column on which to order the status records in the second table.

If your uniqueidentifier is SEQUENTIAL the solution will be:

SELECT TOP 1 WITH TIES T1.[BoxName]
                      ,T2.[Status]
FROM [Table 1] T1
INNER JOIN [Table 2] T2
    ON T1.[Id] = T2.[Table1_FK_ID]
ORDER BY ROW_NUMBER() OVER (PARTITION BY T1.[Id] ORDER BY T2.[ID] DESC);

but if it is not you need to add record_id or date_add columns in order to know which record is the last one inserted.