Problems after crainotomy for benign meningoma

My 72-year old mother had a crainotomy to remove a benighn meningoma Oct. 29. Seventy-five percent of the tumor was removed and she did well the first two weeks, exceeding everyone's expectations. She left the hospital in good shape and moved to a rehab facility for two weeks. In the second week her condition declined. She became lethargic and emotionally distressed, barely able to carry on a conversation or feed herself. We were told she was given two dozes of Zanaz, because of night-time agitation, which we thought accounted for the change. When she arrive home, her condition worsened. She was prescribed 500 mg of dilantin, vicodan , ativan, zyrtec in addition to her regular drugs of Aricept (she had mild dementia), Lexapro. Her dilantiin level read high by the home health nurse and her doseage was dropped by down to 300 mg of dilantin which she had been taking for about nine months prior to the surgery. At first she just wanted to sleep and became agitated a couple of times a day, then the agitation turned into delusional fits in which we walked the floor with her for hours on end until she finally fell asleep. She is now in a hospital, two hours away from her neurosurgeon and her dilantin has been reduced to 200 mg and her pain medication has been upped to dilaudid, along with ativan given intravenously. Her physical condition is good, all vitals are good and she is strong, a CT scan revealec no major stroke (if she had a small one it didn't show up). We are at a loss for what may have caused these problems or how to fix it. We can't figure out if it was from all the different medication (she was only taking Tylenol and an occasional vicodan when she first went to rehab, but was given Zanax and Ribertrol (I think that's what it's called, an anti-psychotic drug). Anyone ever experienced this? She cries out for help for hours in an almost animalistic voice until she is sedated. How could her condition have declined so fast and so significantly within a matter of days? Any ideas? We are desperate and scared to death.