"...One Chinese dr said magnesium chloride is better than mag citrate. Can you clarify why ? ..."
No, I can't clarify that. You would need to ask him for the basis of his statement.
"...And another said a deficiency in salt can also cause hardening of stools...... Sure enough labs revealed a deficiency in sodium"
The body regulates sodium within a narrow range, because getting out of the range isn't compatible with life. Low sodium levels are most often caused by kidney, liver, or heart problems, dehydration, vomiting or diarrhea, or abnormally high levels of a hormone called ADH (antidiuretic hormone) which causes the body to retain large amounts of water. It is fairly rare, and you would know if this were the problem because she would be drinking quarts of water per day.
"...There is neurological issues going on..."
This may be the issue. Nerves in the bowel stimulate the muscles to move in a coordinated fashion of contraction and relaxation called peristalsis. This pushes the food through the system in a coordinated fashion. If the nerve stimulation isn't there, the muscle doesn't move and BMs are less often and harder.
Here is an article you might find interesting: http://emptyingthebowel.com/index.php?option=com_content&view=article&id=98&Itemid=119
"...Any links describing how to strengthen gut biodome in the elderly to produce daily BM would be helpful..."
Food is the key, of course. You have to eat a healthy diet with lots of fruits and vegetables. Yogurt containing probiotics (Activia) is something to try. Probiotics can also help (Florastor, Align, Culturelle).
As I mentioned, a "daily" bowel movement may not be a normal expectation, Many elders only go every 2-3 days.