Brief Answer:
Read below.

Detailed Answer:
I read your question carefully and I understand your concern. Two days is enough time for the drugs to get out of her system and she should start to wake now. The longer the time goes without her waking up the greater the possibility of her having brain damage.
Brain damage is a common complication of the heart attack and the surgery itself. It may be related either to a focal stroke or to diffuse damage due to prolonged lack of brain perfusion.
The stroke can be in the setting of heart arrhythmia related to the attack and surgery which can release blood clots to the brain, or to coexisting disease of vessels supplying the brain with blood (the same process which occludes hear blood vessels causing the stroke can also involve other vessels).
The lack of brain perfusion can be due to heart failure to supply blood due to the attack itself or to the arrhythmias it can provoke. This may be reversed now, but if it was present long enough it may leave residual damage.

So what you should ask the doctors is first whether her management there were any episodes with extremely low blood pressure which might have lead to lack of perfusion.
Second do they notice any focal signs which might indicate a focal brain lesion due to a stroke: such as lack of movement of the limbs on one side, facial asymmetry, impairment of ocular movements, pupillary abnormalities etc.
If no signs of improving could an imaging exam such as head CT be performed (MRI is even better but not sure it's feasible).
If no focal signs and imaging results to be normal are they any signs which might indicate other causes such as seizures. At times an EEG might be considered to capture nonconvulsive seizures.

There are times when all things said and done patients take some days to improve even in the absence of neurological signs and with normal imaging. The causes of this reversible encephalopathy aren't always clear, presumably a transitory suffering due to the temporary lack of blood flow and inflammatory product release in the blood due to the heart attack and surgery. Hopefully your mother's case is such a reversible case as well.

There is not much that you yourself can do or try now, it's a critical complex situation which requires medical expertise, I suppose she's in an intensive care unit, so will be taken care of by the best doctors.

I remain at your disposal for further questions.

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