try this
SELECT u.USER_FNAME, u.USER_LNAME
, COUNT(DISTINCT case s1.form_status when 'C' then s1.SSA_FORM_ID else null end) ssa_pro
, COUNT(DISTINCT case s1.form_status when 'D' then s1.SSA_FORM_ID else null end) ssa_del
, COUNT(DISTINCT i1.INQUIRY_FORM_ID) inq_pro
FROM tbl_USERS u
left outer join tbl_SSA_FORM_STATUS as s1
on u.user_id=s1.user_id
left outer join (select inquiry_form_id,user_id from tbl_INQUIRY_FORM_STATUS
where form_status='C') as i1
on u.user_id=i1.user_id
WHERE u.USER_TYPE = 1
GROUP BY u.USER_lnAME,u.user_fname
ORDER BY u.USER_LNAME ASC,u.user_fname