Running XX_PKGb.sql (a package create statement) from with your PL/SQL block is not allowed. If you must do it there then it needs to be dynamic SQL. 

The better way is to simply run it from SQLPlus;

    set term on
    
    set echo off
    
    set feedback off
    
    set define on
    
    set verify off
    
    ALTER SESSION SET CURRENT_SCHEMA = XXEOM      
    /
    @XX_PKGb.sql
    /
    exit