All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
There are some etiquettes that should be met for a husband enjoying his wife and vice-versa. Such etiquettes should be in concordance with Islamic Law, sound mind and the natural disposition upon which Allaah has created mankind. A spouse putting his finger into his partner's anus and vice-versa does not fit into the above etiquettes, and worse than that is licking each other's anuses. Both acts are very abominable and no sound mind would accept this. Doing such an act repeatedly may lead to a person being tempted by the anus and wish to have sex in the anus, and if so, he would commit a great major sin that is forbidden in Islam. Indeed Islamic Law condemns such an act.
Islamic law has allowed us many permissible ways for a husband enjoying his wife and vice-versa, by which we can repel resorting to the two abominable actions that you mentioned in your question as well as other matters that the Islamic law does not approve of.
Allaah Knows best.