DECLARE @companytable table
(
 companyid int,
 companyname varchar(200),
 countrycode varchar(3),
 city      varchar(30),
 isactive  int
 )
 
 
 insert into @companytable
 select 1,'s1','US','California',1 union all
 select 2,'s2','in','Chennai',1 union all
 select 3,'s1','in','Chennai',1 union all
 select 4,'s6','in','bangolre',1 union all
 select 5,'s5','uk','london',1 union all
 select 6,'s1','uk','london',1 union all
  select 7,'s5','us','newyork',1

 
 DECLARE @boardtable table
(
 boardid int identity(1,1),
 companyid int ,
 createddate datetime,
 isactive  int
 )
 
 insert into  @boardtable
 select 1,'2012-11-01 12:34:49.860',1 union all
 select 2,'2012-11-02 12:34:49.860',1 union all
 select 3,'2012-11-04 12:34:49.860',1 union all
 select 4,'2012-11-06 12:34:49.858',1 union all
 select 5,'2012-11-09 11:34:49.859',1 union all
 select 6,'2012-11-09 11:34:49.860',1 union all
 select 7,'2012-11-09 12:34:49.861',1

select top 4 r.boardid,r.companyid,c.companyname,c.countrycode,c.city  
from
 @companytable c
 join
 @boardtable r
 on c.companyid=r.companyid
 order by createddate desc

boardid companyid companyname countrycode  city
7          7       s5      us      newyork
5          5       s5      uk      london
6          6       s1      uk      london
4          4       s6      in      bangolre

boardid companyid companyname countrycode  city
7          7       s5           us      newyork
6          6       s1           uk      london
4          4       s6          in      bangolre
2          2       s2          in      Chennai
 

--Query for your requirement

Select boardid, companyid, companyname, countrycode, city From 
	(
		 Select b.boardid, b.companyid, a.companyname, a.countrycode, a.city ,ROW_NUMBER() Over (Partition By a.CompanyName Order by b.createddate DESC) As rn 
		 From @companytable as a 
		 JOIN @boardtable as b On a.companyid = b.companyid 
	) As p 
Where rn = 1 
Order by boardid DESC