Does this mean the mother does not like daughter's boyfriend.?

That is a huge age gap. I know people say when you're older, its less weird because legal age but holy moly that man is old enough to be her father.

And either way, its nobody's business so if you don't know then it shouldn't be something to worry about. Maybe the mother doesnt know he has a facebook? or just doesnt go adding everybody she knows? so many reasons.

It probably means the mother doesn't know about the daughter's boyfriend.

Using comparisons of who's Facebook friends with who isn't a good way to operate. Don't read into it.

sounds like it

It does not.