Some more information would be helpful. Is your father a VIP owner and if so what level? How many points does he have, how much are his maintenance fees and where does he own? We can likely figure out what his maintenance fees are based on where he owns and how many points he has.
There are people who are point managers but whether or not they would be willing to take your father on as a client depends on whether or not he is a VIP, what level and how many points he owns.
He can rent through Wyndham's Extra Holidays but they get 40% and he will get a tax form to file. You have to be very careful what you place with EH. Say you list a 7 night stay with them and Wyndham only rents 3 or 4 nights of the 7. He would get nothing for the nights that don't rent which could potentially wipe out any profit he would make on the nights that do rent.
He can also rent stays here on TUG, eBay, Redweek and Craigslist. Learning what and how to rent takes some time and research.
However I would never, ever recommend to someone with no experience in renting that they buy more points for the sole purpose of being able to rent.