You need to clarify the type of facility she is in.
'Assisted Living' is generally a facility offering a room, dining room, social rooms, activities etc., and the resident is there to not have to deal with household upkeep, cooking,yardwork, etc. Residents bring their own furnishings, sometimes are allowed pets, and are usually ambulatory though might use a wheelchair. * *They are not there for primarily medical reasons* *, and that is the 'catch' per IRS rules. Their monthly expense is therefore not considered 'medical', though a few adjunct 'medical' expenses might be allowable, such as podiatry visits. Assisted living places will usually insist a client leave if their situation changes such that they need medical attention, as Assisted Living facilities do not offer medical care. Doesn't mean that if you entered the fees as 'medical expenses' that it would never slip through and be accepted on your return.
If on the other hand, she is in a 'board and care' type place or certain rehabilitative facilities, that offer some medical care, those monthly fees would be deductible.
Sometimes, if someone has long term care coverage, and receives the LTC tax form, it on occasion might be that costs in an 'assisted living' facility would be covered under the LTC policy.