Can a deceased person be aware of the conditions of those who are still alive?

It is established that the Prophet Muhammad (peace be upon him) addressed the dead among the polytheists after the Battle of Badr, spoke to them, and informed that they could hear him (Bukhari, Jana'iz, 86 [1370]; Muslim, Jana'iz, 9 [921]); he also recommended that those visiting graves greet the deceased buried there, and he himself went to the Baqi' cemetery and greeted those buried there (Muslim, Jana'iz, 102 [974]). It is also narrated that the Prophet (peace be upon him) reported that the deeds performed by the living would be shown to their deceased relatives and loved ones, who would rejoice at their good deeds and be saddened by their bad deeds (Tabarani, al-Mu‘jam al-Kabir, 4/129 [3887]). Based on these hadiths, some Islamic scholars have stated that the dead may be made aware of the conditions of the living to the extent that Allah permits.

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu