、。
Mother absolutely cannot drive a car.
Literal
Mother [topic-は], completely car [gen-の] driving [subject-が] cannot-do.
The potential construction [noun]+が+できる / 出来ない. 運転 ('driving') is the nominalized activity, が marks it as the thing one can/cannot do, and 車の運転 ('car's driving') uses の as a possessive-like link. まったく paired with a negative gives 'absolutely not,' 'not at all.'