اللَّهُمَّ بَارِكْ لَهُمْ فِيمَا رَزَقْتَهُمْ، وَاغْفِرْ لَهُمْ وَارْحَمْهُمْ
Allahumma barik lahum fima razaqtahum, waghfir lahum warhamhum
O Allah, bless them in what You have provided for them, and forgive them and have mercy on them.
Dua for the host when being a guest
Making dua for those who host you is from the sunnah.