Maybe tell us exactly what you'd like to do. When you say these users would like to "work from anywhere" what do you mean exactly? Why can't they use their email from anywhere now?
You don't need to move their email to Office 365 for them to have OneDrive, you just need an Office 365 subscription. You don't have to move anything.
As for email, you could move their mailboxes to Office 365 using a Hybrid migration, but why can't they work with their email from anywhere right now? What's stopping them?
Based on your comment to my comment:
You can implement Azure AD Connect to synchronize your on premises AD to Office 365, then you can configure an Exchange Hybrid configuration and move these mailboxes to Office 365 and enable MFA for these users in Office 365. You can purchase the appropriate subscription for these users and leave all other users without a subscription until you're ready to move them to Office 365. That way you're only paying for what you need.