Writing Names for Elevation of the Soul and Blessing
Question
Answer
Shalom Rav
Prayer for living people [for blessing, healing, success, marriage, etc.] - it is appropriate to pray using the mother's name, but it is not mandatory.
Reciting 'Mi Sheberach' after being called to the Torah - the Ashkenazi custom is to mention the father's name. Some Sephardim mention the mother's name, as in any prayer for success, as mentioned above.
In prayer for the deceased, as well as dedications for the elevation of the soul, etc. - the Ashkenazi custom is to mention only the father's name. Among Sephardim, there are different customs. Each custom has its sources.
Similar things were written by the Gaon, Rabbi Ovadia Yosef [Shut Yabia Omer, part 2 - Orach Chaim, siman 11].
Source
Gemara Shabbat 66: 'in the name of the mother'.
Chochmat Shlomo there, that the reason is that lineage through the mother is more evident.
Zohar Chadash Lech-Lecha 84.