Can you add host names to that table?
SELECT T2.name, T1.party_id , T1.host_id, T3.party_theme FROM party_host AS T1 JOIN HOST AS T2 ON T1.Host_ID   =   T2.Host_ID JOIN party AS T3 ON T1.Party_ID   =   T3.Party_ID
add host names to that table refers to joining the table with host names using the host ID;