Russla, MBZ have a dual system. If you lose primary system pressure, there is a backup system further down the master cylinder (so to speak). This requires a great deal of pedal effort and does put the m/c piston near the end of it's travel. If there is air in the system, either at the m/c or in the ABS servos, this will give you the "funny pedal". Not knowing what actually happened in your case, but as you said a line ruptured, there is a good chance you may still have air in the m/c when you lost (I assume) all or nearly all of your fluid. If it hasn't been done the m/c may need to be bled also. I am confused as to why they replaced the ABS assembly, when your casualty sounds like a rapid loss of hydraulic pressure due to a ruptured brake line..did they tell you why the ABS module needed to be replaced. This device has servo valves which can rapidly toggle braking pressure when a wheel loses traction. Don't know why it was replaced. Maybe Steve or Donnie have better info. If I were you, I would find out about that as that component is rather pricey..
2000 Dodge Grand Caravan SE