Wa alaykum salam wa rahmatuLlahi wa barakatuHu,
According to the relied-upon opinion in the Shafi’i Madhhab, a woman may not perform ritual seclusion (ar: i’tikaf) at home, in fact it is is invalid. The mosque is the place of i’tikaf, and a woman’s home is not a mosque. This is confirmed by the fact that it is permissible for her prayer area in the house to be re-designated for another purpose and also it is permissible for one in a state of major ritual impurity to be present in that space. Furthermore, the Prophet’s wives would perform seclusion in the mosque. If i’tikaf at home was valid, then they would have practiced on that. (Tuhfat al-Muhtaj 3/466 & Nihayat al-Muhtaj 3/217)
And Allah knows best.
Answered by Shaykh Yaqub Abdurrahman