^^ both these verse mention prophets passing away before the two prophets mentioned. No exceptions made. As for the mission of Jesus (as) is concerned, it is "a messenger unto the israelites" according to Quran. What will you do with this verse when Jesus contradicts it by becoming messenger unto muslims?
I would encourage you to let them lay out all the supporting material they have on the ascension of Jesus and his being alive for now. We can talk about all the tangents later on.