I'm able to create config.o file by modifying config.c to
#define SS_DBA_GRP "dba"
#define SS_OPER_GRP "dba"
#define SS_ASM_GRP "dba"
also applied Note 11gR2 DBUA Fails With "Null" and trace file shows "Could not launch SQLPLUS. Failed during initialization" (Doc ID 1384810.1)
Still while running the DUA its giving NULL error........
Please share your inputs.