Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
Dear questioner, we would like to thank you for the great confidence you place in us, and we implore Allah Almighty to help us serve His cause and render our work for His Sake.
Answering your question, Dr. Wael Shihab, PhD in Islamic Studies from Al-Azhar University and currently the Imam of the Downtown Toronto Masjid in Canada, states:
As far as Islamic law is concerned, a Christian woman who married to a Muslim man is to observe `iddah (waiting period), just like the Muslim woman, in case of divorce or the death of the husband as this is among the husband’s rights.
It is stated in Al-Mawsu`ah Al-Fiqhiyyah (Kuwaiti Encyclopedia of Jurisprudence, 29:336):
“The Hanafis, Malikis, Shafi`is and Hanbalis, as well as ath-Thawri and Abu `Ubayd, are of the view that the Christian or Jewish woman is required to observe `iddah in case of divorce, annulment of the marriage or death of the husband, just like the Muslim woman, because of the general meaning of the evidence that the ‘iddah is required, and no differentiation is made between them on condition that the husband is a Muslim. This is because ‘iddah is required and is a duty towards Allah and towards the husband…
`Iddah is the husband’ right, and the rights of humans are also due from the Christian or Jewish wife.”
Allah Almighty knows best.