Can those dead know, see, and know-about those alive?
The principle is that the dead do not hear the words of the living, because Allaah says (interpretation of the meaning): "… but you cannot hear those who are in graves." [Faatir 35:22] and
"Verily, you cannot make the dead to hear…" [al-Naml 27:80]
Similarly the dead person does not know anything about the circumstances of his family, because he is absent from them, in a state of bliss or torment. But Allaah may inform some of the dead of some of the circumstances of their families, but this is not necessarily so.