What are the deeds that would increase the scale of good deeds for my deceased mother, and how can I give charity on her behalf despite the scarcity of deserving individuals, and is there a specific supplication I can make for her?

We ask God to have mercy on your mother, and her illness may be a reason for the expiation of her sins and the raising of her rank. After the death of parents, ongoing charity (sadaqah jariyah) should be performed, which is when the principal is withheld and its usufruct is given in charity, thus remaining perpetual. As for charity by spending the principal of the money on beggars, it is not ongoing charity, though the deceased also benefits from it. One can seek out those who use it to obey God. There are examples of ongoing charity and supplications authentically reported for the deceased.