She used to be in her care. A woman asked the Prophet ﷺ about menstrual blood that gets on a garment. He said, "Scrape it off, then rub it with water, then sprinkle it with water, and pray in it."
أخبرنا يحيى بن حبيب بن عربي عن حماد بن زيد عن هشام بن عروة عن فاطمة بنت المنذر
وكانت تكون في حجرها أن امرأة استفتت النبي ﷺ عن دم الحيض يصيب الثوب فقال حتيه ثم اقرصيه بالماء ثم انضحيه وصلي فيه
Bukhari transmitted it, Wudu, Chapter on Washing Off Blood, no. 227, and Muslim, Purification, Chapter on the Impurity of Blood and How to Wash It, no. 291, from the hadith of Hisham, with the same wording. It is also found in Kubra, no. 285.