Is it more befitting for the mother to lead her daughter in prayer, or vice-versa, if the mother is old and does not know the rules of Tajwid, while the daughter knows them but suffers from urinary incontinence?

The leadership of a person with urinary incontinence in prayer for someone who has performed ablution is a matter of scholarly disagreement. Some scholars see no impediment to you leading your mother in prayer. However, it is preferable to avoid this to steer clear of the disagreement. It is better that you put your mother forward to lead the prayer if she has mastered Al-Fatiha, and her lack of mastery in Tajweed does not prevent the validity of her imamate. The congregational prayer of women alone is recommended by some scholars.