Is it permissible in Islam to speak to one's deceased mother at her grave, share daily life details with her, and sleep beside her grave, especially when it alleviates the grief of loss?

There is no harm in a person speaking to his deceased mother when visiting her grave for the purpose of his own comfort, especially since the preponderant opinion is that the dead hear the speech of their visitor. However, it is better to occupy oneself with supplication for her and for the Muslims, or with the remembrance of Allah and reflection on the Afterlife, because this is the purpose of visiting graves. As for spending the night in the graveyard, it is reprehensible in Islamic law due to the desolation it entails, and jurists have explicitly stated its reprehensibility.