I'm looking for a urine incontinence brief that my father can wear (95 yrs) that is re-usable /washable.

They sell them at surgical supplies pharmacies; or they can order them for you. Depending on his insurance, they may pay for them.

They are available from the online stores that sell medical equipment. I did get some for DH and they seemed excessively expensive and inadequate.
Another solution would be to stick a menstrual pad inside his underwear if he would tolerate that. Or you could make your own there are instructions for most things on the web if you are handy

Try googling "washable adult incontinence underwear", but has he really given the disposables a chance? He may be thinking of the bulky, rustling products that were the only thing available years ago, the newer style pull ups are nothing like that (and would save you loads of laundry).