It is the digestive system that is directly impacted by gall bladder removal. Instead of the gall bladder storing up bile to be used in quantitiy for the digestion of fats and proteins, the liver just continously drips bile into the the digestive system. This can tend to irritate the digestive system when it is empty and it is sometimes the case that there is insufficient bile to digest a meal that has a lot of fat in it.
For these reasons, after gall bladder removal it is important for a person to eat many small meals per day rather than two or three large ones, as most people are accustomed to.
When digestion is weakened, then other organ systems do eventually feel the stress, so it is important for your mother to adapt her eating habits to what her body now needs, in order to keep all of her systems healthy.
It is loving of you to be watching out for your mother's needs.