Is the occurrence of disturbing nightmares, in the form of a human threatening to take one's son, despite reading the Quran, Surat Al-Baqarah, and reciting adhkar, an indication of something specific?

It is recommended not to sleep alone, to consistently recite the prescribed remembrances (adhkar) and supplications for protection (ta'awwudhat), and to recite Surat Al-Baqarah with presence of heart and certainty in God's promise, while also protecting one's children with it. This should be coupled with having a good opinion of God, believing that no harm will befall as long as the divine protections are consistently maintained, for Allah states in the Hadith Qudsi: "I am as My servant expects Me to be, so if he thinks good of Me, he will have it, and if he thinks evil of Me, he will have it."