Non catalytic subunit of RNase H2, an endonuclease that specifically degrades the RNA of RNA:DNA hybrids. Participates in DNA replication, possibly by mediating the removal of lagging-strand Okazaki fragment RNA primers during DNA replication. Mediates the excision of single ribonucleotides from DNA:RNA duplexes. The RNase H2 complex is a heterotrimer composed of the catalytic subunit RNASEH2A and the non-catalytic subunits RNASEH2B and RNASEH2C. Belongs to the RNase H2 subunit B family.