Sorry for replying late....
The LoadMonDrvs should be on AmigaoS3.9 CD. Your CD is not VALID or some other release ?! The error may be that there is no LoadMonDrvs in the C: on your CD.
Search LoadMonDrvs on your cd (Workbench3.5/C or Workbench3.9/C ) and copy it manually.If you cant find LoadMonDrvs then get a correct Amiga Os 3.9.
Dary / AmigaSYS Team