Is placing the bed in the corner of the room harmful because it is a dwelling place for jinn, and must one refrain from going to the kitchen and the toilet after sunset in a house with an open roof (a courtyard) because it is exposed to devils, based on the Prophet's (peace be upon him) hadith to avoid going out after sunset?

There is no harm in placing the bed in the corner of the room, as this place is not a dwelling for devils. There is also no harm in going to the aforementioned places in the house at sunset. Rather, young children are preventatively advised against going out into the streets and pathways at that time, as a protection for them from devils. To fortify the house against devils, one should recite the Quran, especially Surah Al-Baqarah, for indeed, the devil flees from a house in which it is recited.