If your data was sorted in descending date order, it would be easy, just set up a filter in the table, and in the advanced tab of the filter definition dialog select "duplicated rows; one row only". I tried sorting your sample in descending date order but the filter is applied to the data by Monarch before the sort is, so that got the wrong result.
In two passes, it's easy enough and as ever, there's more than one way to solve it in Monarch. Easiest is to export the table as fixed width text, with a sort order applied to put the dates in descending order, and then the second model opens this export and applies the advanced filter above.
If it wasn't a date you were filtering on but a numeric field then you could use a summary to do it in one pass. If you don't mind slightly ugly dates then you can do it this way:
Trap the date or convert it using calculated fields so that it is a string of the form "YYYY-MM-DD". Create a calculated field from this called NumDate, defined as val(strip(Date);"-") - this gives you a number YYYYMMDD. Then all you need to do is create a summary where the measure is Max(NumDate).
If you make a calculated field and convert your dates to serial numbers as provided in the tips in this url=http://www.monarchforums.com/showthread.php?t=1261thread[/url], you should be able to create a summary easily enough without having to use a 2-pass process.