My mother has 64 years old....her problem is that she sweats to much in the face, like its "raing... what can it be ? maybe a form of illness ?

I suspect it is: Most likely due to perimenopause/menopause. Due to low estrogen levels. If uncomfortable, hrt may help. Sometimes drugs like Effexor (venlafaxine) do as well. Should prob check thyroid too. Some rare tumors can sometimes cause severe sweating but there are also very noticeable other symptoms associated w these. Finally some medications can cause excess sweating as a side effect.