My friend's mother treats me like her son; am I obligated to honor her?

A Muslim must respect his Muslim brother, especially the elder. Venerating the elder and showing mercy to the younger are branches of faith. The Messenger of Allah, peace and blessings be upon him, said: "He is not of us who does not show mercy to our young ones and venerate our elders." He also said: "Every gentle, kind, easygoing person who is close to people is forbidden to the Fire." And he said: "Do not belittle any good deed, even meeting your brother with a cheerful face."

Therefore, one must honor the mother of a friend, especially if she is a relative or a neighbor. Her righteous treatment is particularly emphasized if she is a mother or an aunt through breastfeeding, for the Prophet, peace and blessings be upon him, used to honor his relatives through breastfeeding. However, if she is not a mahram (definition) to you through breastfeeding or lineage, then she is considered a non-mahram (a stranger), and it is not permissible to shake her hand or be in seclusion with her.