Du'a for a mother's remembrance

اللَّهُمَّ اجْعَلْ أَوْقَاتَهَا بِذِكْرِكَ مَعْمُورَةً

Allahumma-j'al awqataha bidhikrika ma'murah

O Allah, make her time filled with Your remembrance.

A general supplication, not a narration from the Prophet (peace be upon him).