My father passed away in a hospital 300 Kilometers away from home (Jammu city) after meeting a road accident. My mother was along with him. My parents lived in kashmir (Indian side of Jammu and Kashmir state). We brought the body of our father to our home and our mother accompanied. Can my mother travel to join her grandson's Nikah ceremony during Iddat period.
In the name of Allah, the most Beneficent, the most Merciful.
During the period of iddah the bereaved wife should remain in the house she and her husband occupied. It is not permissible for her to leave the house unless there is a necessity or in extreme emergency. (Hidayah p.428 v.2)
Regarding your question, it will not be permissible for your bereaved mother to go to her grandsons nikah as it does not constitute necessity.
Only Allah Knows Best
Mohammed Tosir Miah
Darul Ifta Birmingham