I would provide the standard Lacerte Backup. Highlight all the clients and use Ctrl + B to back them up. That should contain everything they will need to to a conversion. If we knew which software it was going to, that could help, as they likely have specifics needed. 

For example here is what ProSeries wants - Notice NO LOCKS, NO PASSWORDS

https://proconnect.intuit.com/community/convert-data-files/help/lacerte-backup-instructions-for-data...