You cannot password protect the DBF files themselves.
You can password protect your
VB front-end application and you can encrypt the DBF file data using a variety of encryption/decryption utilities from the web.
Another way of 'fooling' un-wanted users is to use a different file extension for your data tables instead of .dbf VFP will not care as long as you specify the full filename + extension. I am not sure what
VB will do. I guess it depends on how you are doing your table access.
Good Luck