/usr/include/libbson-1.0/ is in libbson-dev 1.3.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libbson-1.0/bcon.h
/usr/include/libbson-1.0/bson-atomic.h
/usr/include/libbson-1.0/bson-clock.h
/usr/include/libbson-1.0/bson-compat.h
/usr/include/libbson-1.0/bson-config.h
/usr/include/libbson-1.0/bson-context.h
/usr/include/libbson-1.0/bson-endian.h
/usr/include/libbson-1.0/bson-error.h
/usr/include/libbson-1.0/bson-iter.h
/usr/include/libbson-1.0/bson-json.h
/usr/include/libbson-1.0/bson-keys.h
/usr/include/libbson-1.0/bson-macros.h
/usr/include/libbson-1.0/bson-md5.h
/usr/include/libbson-1.0/bson-memory.h
/usr/include/libbson-1.0/bson-oid.h
/usr/include/libbson-1.0/bson-reader.h
/usr/include/libbson-1.0/bson-stdint.h
/usr/include/libbson-1.0/bson-string.h
/usr/include/libbson-1.0/bson-types.h
/usr/include/libbson-1.0/bson-utf8.h
/usr/include/libbson-1.0/bson-value.h
/usr/include/libbson-1.0/bson-version-functions.h
/usr/include/libbson-1.0/bson-version.h
/usr/include/libbson-1.0/bson-writer.h
/usr/include/libbson-1.0/bson.h