Actually what Hospice told you was right. If there is a question about the side effects or effectiveness of the Namenda they you should give a half dose and see if it gets better or worse. It is standard practice in medicine that is probably not used enough
By the time Hospice is contacted most patients are off the Namenda/Aricept medications. Hospice uses different medications to control symptoms of the disease rather than a medication that is designed to slow the disease. Haldol is a medication that has been used successfully for many years to control the mental distress because it has so few side effects.
So what you heard from your Hospice staff is exactly what I have heard many times before. It's not off the cuff, though might have appeared at such. Remember... the Namenda/Aricept will not take Mom back to where she was. Your doctor was not correct in saying we can always put her back on. If she does decline when the meds are stopped there is no getting that back. Putting her back on the medication will at best slow from where she is the moment they put her back on the meds.