Kallah, yes you have good instincts and you are on the right track. It would be appropriate for you to bring something. The suggestion that you bring pictures in a nice album or a nice picture of you and the chasson in a very nice frame if you haven’t done that already is probably the best idea.
The next to the best idea is to bake chocolate chip cookies (who doesn’t like them), which are the easiest cookies to bake and bring them on a very nice platter that they would be very proud to use again.
Those are the two simplest and least awkward things to do. The next in line is flowers, but that is something that is not so special because your father-in-law might get his wife flowers on a regular basis.
My daughter-in-law came with a cookie jar filled with home made chocolate chip cookies the day she came to meet us. That was an unusual move and totally not necessary but very impressive and thoughtful.
Keep it small and thoughtful.