Is it permissible for a wife whose husband has passed away to leave her home to attend her daughter's wedding, even though only a few days remain until she completes her iddah, and that is without adornment and for a short period?

There is no objection to a woman in 'iddah leaving her home to attend to her needs and affairs, including attending her daughter's wedding, as long as she does not go out to commit a sin. The majority of scholars have held that she may go out during the day for a need, and it is permissible at night according to the majority, provided that she does not spend the night except in her home and that she refrains from adornment. The proof for this is what Muslim narrated from Jabir (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) said to his aunt, who was divorced and wanted to harvest her date palms: "Yes, go and harvest your date palms, for you may give charity or do a good deed."