PL/SQL :: Single Query Return Multiple Value

I have a sql query as below :

select order_number,
(select decode(hcp.contact_point_purpose,'ABC',hcp.email_address,'CDE',hcp.email_address,null)
from hz_contact_points,
hz_parties hz
WHERE hz.party_id=hcp.owner_table_id) Email
FROM oe_order_headers_all h
WHERE h.order_number='102'
....................
..............

Actually the problem i am facing is the inner select query is returning multiple row , so my main query is erroring out, i need to capture the multiple row.

In the above example the inner decode statement returning two mail address, I need to capture that, but while executing the whole query it is erroring out as saying single query returns multiple values. capture multiple values