What are the best deeds whose reward reaches the deceased, and what is the ruling on prayer, fasting, charity, 'Umrah, Hajj, reciting the Qur'an, and supplicating for the deceased, given that the deceased mother missed some prayers and fasting due to illness?

Among the acts of filial piety towards parents after their death are: supplicating for them, giving charity on their behalf, and maintaining ties with their relatives and friends. Prayer on behalf of the deceased is not prescribed, but some scholars have permitted donating the reward of supererogatory prayers to the deceased. It is recommended to fast on behalf of the deceased if they had missed fasts to make up, and it is permissible to perform voluntary fasts and donate their reward, as well as to offer expiation if it was due from them. Similarly, giving charity and donating its reward is prescribed, as are 'Umrah and Hajj, and reciting the Qur'an and donating its reward to the deceased.