As-salaamu `alaykum
After mentioning the opinions held by scholars and which one you feel inclined to (as the truth), why not ask her about these passages from the Bible?
Now therefore kill every male among the little ones, and kill every woman that hath known man by lying with him. But all the women children, that have not known a man by lying with him, keep alive for yourselves.
[Numbers 31:17-18]
And to the others he said in mine hearing, Go ye after him through the city, and smite: let not your eye spare, neither have ye pity: Slay utterly old and young, both maids, and little children, and women: but come not near any man upon whom is the mark; and begin at my sanctuary. Then they began at the ancient men which were before the house.
[Ezekiel 9:5-6]
And the city shall be accursed, even it, and all that are therein, to the LORD: only Rahab the harlot shall live, she and all that are with her in the house, because she hid the messengers that we sent. And ye, in any wise keep yourselves from the accursed thing, lest ye make yourselves accursed, when ye take of the accursed thing, and make the camp of Israel a curse, and trouble it. But all the silver, and gold, and vessels of brass and iron, are consecrated unto the LORD: they shall come into the treasury of the LORD.So the people shouted when the priests blew with the trumpets: and it came to pass, when the people heard the sound of the trumpet, and the people shouted with a great shout, that the wall fell down flat, so that the people went up into the city, every man straight before him, and they took the city. And they utterly destroyed all that was in the city, both man and woman, young and old, and ox, and sheep, and ass, with the edge of the sword.
[Joshua 6:17-21]
Now go and smite Amalek, and utterly destroy all that they have, and spare them not; but slay both man and woman, infant and suckling, ox and sheep, camel and ass.
[1 Samuel 15:3]
Samaria shall become desolate; for she hath rebelled against her God: they shall fall by the sword: their infants shall be dashed in pieces, and their women with child shall be ripped up.
[Hosea 13:16]
Alhamdulillah, Islaam truly is a religion of mercy!!! Many "Judeo-Christian" countries of the West are meting out these acts of pure savagery and then covering their deeds and then put the spot-light on a few bands of wrong-doers in the Muslim world. We won't forget Iraq, Palestine, Afghanistan, Bosnia or anywhere else where such Biblical verses were implemented, and the UN just sat there and watched.
Look at Islaam however. We're totally prohibited from these heinous crimes, yet we are told that in an event that there happens to be women and children in a place under attack, that it doesn't need to be held back because of their presence. On the other hand, in the Bible we read that infants should be diced and slashed?
Allah knows best.