The statement that best describes the situation Monna finds herself in is:
She is upset because in order to save her son she must take something from a man who has already ruined himself.
Monna is conflicted because she recognizes that Federigo has dedicated himself to her and has suffered greatly due to his unrequited love for her. Asking for his falcon, which is not only his prized possession but also his means of support, feels insensitive to her given the context of his sacrifices and struggles.