Whoever accompanied the funeral should not return home without offering the funeral Ṣalāĥ; after the Ṣalāĥ, he may return, seeking permission from the family-members of the deceased person. There is no need to ask permission for returning after the burial. (‘Ālamgīrī, vol. 1, pp. 165)
The husband is allowed to carry his wife’s bier on his shoulder, lower her in the grave for the burial and see her face. He is prohibited only from bathing his wife and directly touching her body (without cloth etc., in between). A woman can bathe her husband. (Baĥār-e-Sharī’at, vol. 1, pp. 812, 813)
There is the same ruling for funeral of an apostate and a disbeliever. Once a query was asked in the court of A’lā Ḥaḍrat, Imām-e-Aĥl-e-Sunnat, ‘Allāmaĥ Maulānā Shāĥ Imām Aḥmad Razā Khān عَـلَيْهِ رَحْمَةُ الـرَّحْمٰن about a person who had converted from Islam to Christianity. In reply, he رَحْمَةُ اللهِ تَعَالٰی عَلَيْه writes on page-170, volume 9 of Fatāwā Razawiyyaĥ that if it was proven as per Shar’ī criteria that the dead had, Allah عَزَّوَجَلَّ forbid, changed his religion and adopted Christianity, (etc.), performing his funeral Ṣalāĥ, shrouding or burying him like that for Muslims – are all absolutely Ḥarām. Allah عَزَّوَجَلَّ says in the Holy Quran: