smokey muffler

She shouldn't drive it too much, especially if the engine is overheating. White smoke is normally due to engine coolant burning in the engine, and this is normally from a blown head gasket. If you take it to a repair shop, they can check this fairly easily, unfortunately, if the headgasket is bad, it will require an expensive repair. https://repairpal.com/testing-for-head-gasket-failure https://repairpal.com/estimator/head-gasket-replacement-cost