What are your (father-in-law's) expectations? Software that ran on the Mac II won't run on the new Apple machine, as there are too many generations of Mac OS between the two. The data (i.e. files) could likely be translated from, for example, from whatever word processor or spreadsheet he used to modern equivalents. A company like RetroFloppy could take a drive and translate the files. If you wanted to do it yourself, you'd need a way to connect the old drive to the new machine - like an external enclosure that spoke USB out one end, and could accept a SCSI drive internally. That could allow you to mount the drive directly to the new machine and copy the files directly. Then you'd need a way to translate the files you had to whatever software is (going to be) in use on the new machine.
It is going to be tough to transfer data from a old SCSI drive to an ATA or Sata drive in a newer Mac. I found some threads that adresses the problem with no easy solution. I take it there is no backup.