How would you repair a small hole about a 1/4 inch in a roadrunners headliner, rest of liner in good condition. thanks need ideas

You can look at auto parts store to see if they have that iron on vinyl fix stuff. Depending on where the hole it, you may never notice the repair.

BTT

....add another dome light....

Where is the hole?

Another idea would be to remove a trim strip and cut off a small piece of material from a hidden area.
First glue a slightly larger piece behind the hole by working it through the hole. Let that dry well first,
then fit a patch the exact size of the hole & glue it in place.
If needed, some small dabs of vinyl repair material around the edge should make it nearly in-detectable...

Rick

How old is the headliner now? If it is pretty old but liiks ok on the outside I would bet it is not so good on the inside...

I would say replace it... Do it once and do it nice... It will then last many many years....