Is it permissible for a woman whose husband has died to go for Umrah or to visit her husband's grave during the waiting period (iddah), and would she be sinful if she went out for either of these two reasons?

It is obligatory for a woman whose husband has died not to travel, neither for Umrah nor for any other purpose, and to remain in her husband's home until her 'iddah (waiting period) ends. As for women visiting graves, this is a matter of scholarly disagreement. One group holds that it is not included in the permission to visit graves, while another group deems it permissible if temptation is avoided and she is accompanied by a mahram. Ibn Hajar transmitted from Al-Qurtubi that the prohibition might be due to neglecting the husband's rights, displaying adornment (tabarruj), and wailing. If these matters are avoided, there is no objection, because remembering death is needed by both men and women.