Dear Ash,
I will pass on my experience in the high amonia level experience.  My husband had only two (2) really bad experiences with the high level and both were terrifying.  He too was prescribed lactulose which does work somewhat, but the side effects are not so good.  He was then prescribed Xifaxan.  This medication helps take care of the bacteria that causes the high amonia levels and he has not had another episode in 5 months.  If you talk to your Mom's doctor and he agrees that this might help, be sure to ask for SAMPLES.  This medication is approximately $1400. for 1 month (60 pills). It is covered by most Medicare Part D providers if the treating physician will complete their form that simply states the alternative medications (lactulose) is not getting the job done.  As for the smoking, I have tried to get my sister and brother to quit - they are still at it, my brother has had to have stints for hear problems and still continues and I too am upset with them.  After seeing up close what I have had to go through with my husband's cancer they still have the audacity to light up immediately after walking out my front door!

Hope this info might help you -
Take Care
BJS