Which is better: to allocate 100 riyals to my mother as an act of upholding kinship ties out of 300 riyals designated for charity, or to continue donating the full amount?

May Allah reward you for your eagerness to do good. Your kindness and good treatment of your mother are among the greatest acts of nearness [to Allah]. If giving money to your mother brings her joy and provides her comfort, then give her this money even if she is not in dire need of it, out of eagerness to be dutiful to her and in desire for her pleasure, because the pleasure of the Lord is from the pleasure of the parent. By doing so, you will have combined the benefit of being dutiful to your mother and charity. And if you give other charity to the needy in addition to your mother's share, this is good, for Allah Almighty replaces what you spend.