Law of Close Notification for Other Relatives

A person passed away, and his death was concealed from his mother due to her health. Two weeks later, she tried to contact him and had to be told that he had passed away. Does she need to perform keriah and sit shiva at the time of the notification?

She needs to perform keriah, and afterwards have the meal of consolation. If her health does not prevent her from sitting shiva, she should also sit shiva and observe the laws of the thirty days from the time of the notification.

It is stated in the Gemara Moed Katan, page 20a: "The Rabbis taught: A close notification requires observing seven and thirty days, a distant notification is observed only one day. What is close and what is distant? Close - within thirty days, distant - after thirty, according to Rabbi Akiva." And so it is ruled in the Shulchan Aruch, Siman 402, paragraph 1: "One who receives notification of a relative's death, if the notification comes within 30 days, even on the 30th day itself, it is a close notification, and he is obligated to observe seven days of mourning from the time of the notification; and he tears his garment and counts 30 days." The Rema writes: "From the time of the notification" for haircutting and other matters. In general, the day of close notification is like the day of burial.