I never heard of the brand. Usually no-name guitars are really cheap. It LOOKS cheaply made--for instance the top is not spruce (it's probably plywood!) and the rosette is painted on, rather than inlaid. And if your grandfather bought it but doesn't remember it, if he doesn't PLAY guitar, it was probably a cheap 'beginner's' instrument back when he bought it.
But what a guitar is worth depends on how it plays, how it sounds. Anyone you know who's played guitar for a few years could try this one and tell you 'This is a pretty good guitar!' or 'This is a piece of crap'.
The market for used cheap guitars is flooded. (Even NEW cheap guitars!) So I'm guessing it's not going to bring in a lot of money. Maybe $100 if you're lucky.
Sight down the neck from the head to the body. If the neck is not perfectly straight, if it's bowed from years of string tension, the guitar is worth NOTHING. It's no longer a musical instrument, it's now just a decoration to hang on the wall.