How to be sure previous owner vacates

[Alexandra Page]

My husband & I just bought a home at auction in MA to flip this spring - it is currently occupied.  He is considering offering a $1000-1500 for them to vacate just prior to closing for us to be able to get started with the rehab right away & hopefully entice them to not trash the place vs. having to serve them, potentially hire bonded movers, etc.  Does anyone have any experience doing this sort of thing to soften the blow for a couple who just lost their house?

Thanks in advance!