/usr/include/ql/methods/montecarlo/ is in libquantlib0-dev 1.4-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ql/methods/montecarlo/all.hpp
/usr/include/ql/methods/montecarlo/brownianbridge.hpp
/usr/include/ql/methods/montecarlo/earlyexercisepathpricer.hpp
/usr/include/ql/methods/montecarlo/exercisestrategy.hpp
/usr/include/ql/methods/montecarlo/genericlsregression.hpp
/usr/include/ql/methods/montecarlo/longstaffschwartzpathpricer.hpp
/usr/include/ql/methods/montecarlo/lsmbasissystem.hpp
/usr/include/ql/methods/montecarlo/mctraits.hpp
/usr/include/ql/methods/montecarlo/montecarlomodel.hpp
/usr/include/ql/methods/montecarlo/multipath.hpp
/usr/include/ql/methods/montecarlo/multipathgenerator.hpp
/usr/include/ql/methods/montecarlo/nodedata.hpp
/usr/include/ql/methods/montecarlo/parametricexercise.hpp
/usr/include/ql/methods/montecarlo/path.hpp
/usr/include/ql/methods/montecarlo/pathgenerator.hpp
/usr/include/ql/methods/montecarlo/pathpricer.hpp
/usr/include/ql/methods/montecarlo/sample.hpp