Is working as a cleaner and cook in the home of a Christian, non-Muslim man, living with him and serving him food—with the exception of pork and alcohol—while maintaining hijab and prayer, considered haram?

The aforementioned work is forbidden and impermissible due to the presence of khalwa (private seclusion) and spending the night with a non-mahram man. This is forbidden even if he is very old, based on the Prophet's (peace be upon him) saying: "No man should be in seclusion with a woman unless a mahram is with her," and his saying: "No man is in seclusion with a woman but Satan is the third of them." In addition to that, this work involves serving a disbeliever, and some scholars deem this impermissible as it entails humiliation for a Muslim. Therefore, one must repent to Allah, abandon this work immediately, and seek permissible employment.