mp4 to vob(?) conversion - numpty help required

[D1MAC]

I'm looking to convert/transfer some mp4 files for my old man into a format that can be played on any old dvd player (and I'm assuming that only vob will achieve this).

Anyone any ideas on the best/easiest way to do this. Something simple and cheap/free would be appreciated as I would like to show the old chap how to do this under his own steam and he isn't remotely technical (but can follow instructions with a little phone guidance).

TIA