My mother also suffered a stroke when she was had surgery at the age of 75 and also had and suffered from aphasia.  She started smoking at age 16 and smoked for 45 years at that point before quitting.  She tried to quit for years and successfully quit when she had pneumonia and congestive heart failure and prior to my oldest son's birth in 1985.  After her stroke in 1999 she was in a rehab for 100 days.  She was able to get back her mobility to a certain degree and was able to use her arms and walk without assistance for awhile but was also a type 2 diabetic at that point and had neuropathy in her feet.  She was able to say words and names but would get her words confused sometimes and names.  She was never able to gain her full speech back but could say words.  The speech therapy definitely helped but she reached her medicare limit and at that point the therapist felt she had gotten as far as she was capable.  She seemed content that she was able to say words to communicate.  She probably also had her health conditions and age going against her.  I'm so sorry to hear about your mother not being able to speak words.  I'm sure there are so many things she would like to say that are locked inside and are going unsaid.  Please try to communicate, smile and be positive for her sake.  Miracles do happen sometimes.

My Mom's speech therapist very patiently taught her to shape her mouth to form words again. Just like a baby. We started with single words and eventually moved on to now making sentences 7 years later. Best therapy is talking to them in short simple sentences. Start with basic words one at a time encourage her to watch you shape the word with your mouth. Hope this helps.