"Common sense" only exists in the minds of "normies" not addicts.
Tobacco is allegedly more addictive then Heroin.

She can bounce back very quickly once she is re-hydrated.

I would suggest that you seek out a support group, caregiving for one and Alanon and possibly ACA as well and get some help for yourself. It might seem strange but it's not your mother who has the problem.

These kinds of problems don't just happen in a weeks time. This must be an ongoing issue. I am surprised that she got by without a full time caregiver as long as she did, alcohol, tobacco or not.

I also have to ask what kind of pain management protocol is she on? The alcohol can have deadly side effects when combined with many narcotics or is she undermedicated and medicating herself with alcohol (and thats got to be tough since, like Marcus said, it must burn like hell).

Being a caregiver can be very difficult with the best of patients. In many ways it is far more difficult than what a patient goes through. Get some help and respite care for yourself. Set some boundaries about the smoking in the house- but not ultimatums - just consequences and choices. It is a gift to caregive and also an obligation right out of the 10 commandments. It may not seem like it now but if you can get through this to the other side it will be much easier living with yourself knowing that you did all you could, rather than second guessing yourself.