Which exit off Rte 128 should I get off, coming from the south?

I agree with the 20B option. You'll hit all major rods until you get to Linden street. I would take 9 to 16 to Linden. I think that's the way.

You have two options depending on how quickly you want to get off the highway. The first is Exit 17, which is Route 135 and will run you through Needham Center. The second (more highway) is Exit 20B for Route 9, which you follow until Kingsbury St, which will then take you to Linden St where Capt. Mardens is. This last route is probably the most direct.

Route 9 West will get you there