Praise be to Allah, prayer and peace be upon the Messenger of Allah and upon all His Family and Companions.
We invoke Allah to bestow his mercy and forgiveness upon your husband and to give you the strength and patience to overcome this calamity. It is impermissible for a wife (a widow in her waiting period ) to travel for Hajj or Umrah, or to leave her house except for a necessity or a dire need .Allah ,The Almighty, says : “And those of you who pass away, leaving wives, they shall wait by themselves for four months and ten. When they have reached their term, then you would not be at fault regarding what they may do with themselves, honourably; God is aware of what you do. “ {Al-Baqarah/234}.
It should be noted that Hajj is an obligatory act of worship which a Muslim performs at times of comfort i.e. she/he is financially and physically capable, and the route of travel is safe. Therefore, a wife observing Iddah is not sinful in Sharia if she postpones her Hajj to the following year. “ If her Iddah was due before leaving her house, then she must never leave it, but if it was due while she was out of her house, but within the boundaries of her area of residence, then she must return home, according to the more correct opinion of the Shafiee school of thought” {Mughni Al-Mohtaj ( 5/108)}.
“Leaving her house during Iddah ,except for a legitimate excuse , is a major sin in Islamic Sharia because staying at her house preserves Allah`s right on her through the protection of lineage…etc.” {Al-Zawajir A`nn Iktiraf Al-Kabba`r by Ibn Hajir Al-Haitimi 2/101}. And Allah knows best.