Is it permissible for women to hold a study circle or lesson specifically for themselves in the mosque or in their homes, or are they only required to attend the study circles of scholars?

There is no objection to dedicating a study circle for women in the mosque or in homes; it is a praiseworthy act. The Messenger of Allah (peace be upon him) designated a day for teaching women, as he said: "Gather on such and such a day, in such and such a place." Seeking knowledge is better than wasting time. A woman's intention in this should be to worship Allah, remove ignorance from herself, and teach others.