If your mother had stroke
the most important thing to rule out is that she is not aspirating ie the food she eats is not going in her lungs.
That means that the swallowing is normal and the chest is clear.
Secondly you must see that she is not having reflux disease and the food she eats should not come up from stomach in the throat.
Get her examined.
And take precautions like--
Keep head end of bed elevated.
Avoid spicy and oily food.
Get done fiber optic examination of the throat and get examined for any Vocal cord paralysis
. ie her vocal cords are moving properly and especially closing when swallowing.