Can I build a house where there is a monk’s tomb?

Yes. Many of today's communities are built on original cemeteries, and the monks have merit and blessings. A cemetery that I passed by when I was going to school is now a high-end community, and a cemetery in our village is now a resettlement community with many high-rise buildings. There are no Feng Shui taboos. However, before houses were built in these places, the tombs had been moved away.