Needed a dummy month to be displayed - Oracle SQL

You can use partition by extension of outer join to achieve that. Here is an example:

-- sample of data from your question SQL> with fees_status(REG_ID, DOP, MONTH1, STATUS) as(  2    select 'AE-8', to_date('7/1/2012', 'MM/DD/YYYY'), 'July,2012'     ,'PAID' from dual union all  3    select 'AE-8', to_date('9/1/2012', 'MM/DD/YYYY'), 'September,2012','PAID' from dual union all  4    select 'AE-8', to_date('11/1/2012', 'MM/DD/YYYY'),'November,2012' ,'PAID' from dual union all  5    select 'AE-8', to_date('12/1/2012', 'MM/DD/YYYY'),'December,2012' ,'PAID' from dual  6  ), -- dates  7  dates(dt) as(  8    select add_months(to_date('01/01/2012', 'mm/dd/yyyy'), level - 1)  9      from dual 10    connect by level <= 12 11  ) 12  select t.reg_id 13       , d.dt as dop 14       , to_char(d.dt, 'fmMonth, YYYY') as month1 15       , Nvl(t.status, 'NOTPAID')       as status 16   from fees_status t 17   partition by (t.reg_id) 18   right outer join dates d 19      on (d.dt = t.dop) 20   where d.dt between (to_date('1-Jul-2012', 'dd-Month-yyyy')) 21                  and (to_date('1-Dec-2012', 'dd-Month-yyyy')) 22  ;REG_ID DOP         MONTH1                STATUS------ ----------- -------------------- -------AE-8   01-Jul-12   July, 2012            PAIDAE-8   01-Aug-12   August, 2012          NOTPAIDAE-8   01-Sep-12   September, 2012       PAIDAE-8   01-Oct-12   October, 2012         NOTPAIDAE-8   01-Nov-12   November, 2012        PAIDAE-8   01-Dec-12   December, 2012        PAID6 rows selected

WITH MONTH_COUNTER AS (  SELECT LEVEL-1 AS ID   FROM DUAL   CONNECT BY LEVEL <= 12) SELECT TO_CHAR(ADD_MONTHS(TO_DATE('01/01/2012', 'DD/MM/RRRR'), ID),'dd/mm/yyyy') FROM MONTH_COUNTER;

This will create a dummy table contains all the months of a year mentioned. Do a left joinon this to get your requirement.

Hope this helps!!