Books Online ( BOL ) is a nice place to start with

Select * from Employees_Table where employeeid not in (Select employeeid from employee_Table a , MeetingAttendance  b where a.employeeid = b.employeeid and meetingid = @meetingid and meetingdate between @fromdate and @todate)

Select * from Employees_Table where employeeid not in (Select employeeid from employee_Table a , MeetingAttendance  b where a.employeeid = b.employeeid and meetingid = @meetingid and meetingdate between @fromdate and @todate)