ASK A QUESTION The word "su madre" means his, her, your, their mother.
I would like if the word "su" applies to his, her, their and your?
This is correct, ria, welcome to the forum
Yes, it can mean all of those.
la madre de él
la madre de ella
la madre de usted
la madre de ellos
la madre de ellas
la madre de ustedes
la madre suya
Yes it does, but be careful, that same expression can be an insult! It depends in the context and the tone of voice used.