She had a dream with Roman waking her up, and telling her she has short time to live, and speaks how meaningless life is and how it ends, so there's no point in restoring humanity, and save the world. Why bother if people are just going to die? Everything is meaningless. Mash snaps and says he's not doctor Roman, he wouldn't say such a thing  because even if Roman is pessimistic he wouldn't deny the worth of human history, and then you see the dream Roman getting glowing red eyes and facial marks and his image switches to Solomon's. She awakes and asks Roman if life has any meaning, so objectively, it doesn't. But living our lives, you know, by the way it ends, and how it impacts others that's the meaning in the end. The journey in other words.

Of course Ritsuka moment is all anime only, she/he doesn't have deep thought about it or any philosophical stand. One of the phrases to beat Quetz is just a meme. The scene was to establish Roman is the ideological opposite of the last boss.