What is the ruling on a husband staying overnight with his daughters in their private residence, knowing that there are two unfamiliar girls (friends of his daughters) also staying overnight with them in the same residence?

Ibn Abbas, may Allah be pleased with them both, reported that the Prophet, peace and blessings be upon him, said: "A woman should not travel except with a mahram, and no man should enter upon her unless she has a mahram with her."

If a man's daughters are trustworthy, there is no impediment to him spending the night with them in the presence of two unrelated girls. However, it is preferable and more cautious to avoid this, or at the very least, he should not spend the night in the same place as the two unrelated girls.