with the 56 rows in your sample data...to cover all possible combinations will generate 72 057 594 037 927 935 rows  (2^(56) -1) ....:w00t::w00t:

just a word of caution here....the solution is using MAX(ref) ...which works for your data as posted....but consider the following data. This does not deliver the "previous row"

a helping hand 😀  (courtesy of http://www.convertcsv.com/csv-to-sql.htm  ...simple cut and paste !)

CREATE TABLE #yourdata(
 USERID  INTEGER NOT NULL
,StartDate DATETIME...

http://www.sqlservercentral.com/blogs/lynnpettis/2009/03/25/some-common-date-routines/

any links to code/data sources to generate this 1 million row "Names" table please?

maybe....

CREATE TABLE #somedata(
 ID  INT
 ,CN  INT
,Cstatus VARCHAR(8)
);
INSERT INTO #somedata(ID,CN,Cstatus) VALUES
(1,1001,'active'),(2,1002,'inactive'),(3,1003,'active'),(3,1004,'inactive')
,(4,1005,'active'),(4,1006,'active'),(5,1007,'inactive'),(5,1008,'inactive');

WITH statuses as
(  SELECT ID,

maybe....

WITH ndate
  AS (SELECT *,
      ROW_NUMBER() OVER(PARTITION BY ins_id ORDER BY ABS(DATEDIFF(day, end_date, @thedate))) rn
   FROM #temp)
  SELECT *
  ...

without seeing sample data ...here;s a best guess sample idea

CREATE TABLE #yourdata(
 PID INT
,tdate DATETIME
,tdesc VARCHAR(8)