No idea on that or their value. If they are professionally mounted and framed I would probably pick them up, regardless if they are real or print...if you like them. Different story if you plan to flip. You should be able to decipher if they are real or not by close inspection, however water color can be much trickier ...than say oil paintings. Keep in mind at nearly 80 years old, he may not be around much longer...if they are real, it might be good to hang on to them a few years.
Even the prints of his stuff runs about 40-50 bucks - unframed...and framing is outrageously expensive. Although I can't find one that looks like the one you pictured...could be a good sign.
This would just be for the house, not to flip. But I don't really want to buy a print. I'll go take a look again tomorrow and decide.
Here are two more of them: