Brake pedal went to the floor seemed I would have no brakes?

Brake pedal went to the floor seemed I would have no brakes. I took van to the mechanic $600.00 for new master cylinder and more (do not have the list yet) left the shop drive in van and ABS brake went bonkers for a moment going five mph no problems with road etc (seemed like right front). Took van around town doing errands seemed okay. Got on highway for a forty three mile trip home. At sixty mph van began hard, horrid strong nasty vibration, not a shimming it was like nothing I ever experienced before. Nearest exit was miles away by the time I reach exit the vibration had subsided for the most part. Later, van loaded with groceries I continued home. Exiting the highway began braking about sixty to sixty five mph and van pulled hard to right. Tested her numerous time always at any speed she pulled hard to right while braking. Took van back to the shop before Thanksgiving she is still there. I believe it was faulty workmanship (electricity had gone out for hours while work was being done) or faulty parts. Mechanic is nice gut. Husband is Nam vet and I do not want him to get angry. Mechanic cannot figure out problem. I now have a worthless van unless a miracle happens are you the miracle. Could you call the mechanic and talk to him so I do not need to get my defective van with an angry husband. After all it is the holiday season. Thanks