‘Mother’ on the golf course is simply short for ‘Motherfucker’.
I'm very proud to don't know a thing about this posh game.
Here in Scotland at least it's not necessarily just a posh game.
My band played a gig at a golf club recently. It was in a very working class area and the members were all goo, down to earth ordinary people. It made me really happy that there was somewhere for these people to play the sport they love (I don't play golf myself). The local council also runs several courses where anyone can play and the costs are reasonable.