Can the souls of the Prophets, the Companions, and the Family of the Prophet communicate with people? And is what happens to us—hearing their whispers and seeing them in waking and in sleep—a real thing?

Seeing prophets and righteous people after their death, and their spirits communicating with the living, and speaking to them in whispers, are among the innovations (bid'ah) and delusions of the Sufis. This is from the whispers of Satan and his manipulation of jinn and humans, and his misleading of those who obey him.

These visions are demonic fantasies and imaginings. And whoever thinks that it is a vision of the Prophet, peace be upon him, while awake, has realized the corruption of his statement through the beginning of reason, because that would necessitate his coming out of his grave, and his being seen in multiple places at one time in different forms.

The scholars have condemned those who claimed to have seen the Prophet, peace be upon him, while awake, so how about others among the prophets and righteous people?

The advice is to stay away from innovations and their people, and to adhere to what the predecessors of the Ummah were upon, and to study books of sound creed.