Till now, candy crush doesn't even know whether the father is getting any monthly payout from CPF.
Hence, you guess and I guess only
Because his RA is zero, my first guess was the father could have opted for CPF Life payout. But it is also possible that the father could have a low RA at 55 and hence the RA, with min payout of $250 starting at age 60 or 62 under RSS, could have been exhausted by now.
(note - based on his age, he could have started retirement payout before the introduction of CPF Life).
By 55, we don't know how much OA he has used for payment of property as that would give an idea of how much SA he had for RA.
From 55 to date, about 70k had been paid for the property and how much is from CPF we don't know. Likely before the creation of RA at 55, he could have reserved his OA from being transferred to RA.
So until candy crush finds out, both possibilities exist.