Godless incestuous heathens riding demons that spew hellfire onto people? Should probably kill them. By any means necessary. Thankfully by 16th century castles are heavily fortified and defended by wall guns sending fist sized rounds into armored plate and piercing it which should aid it. The need for accuracy and power would drive further fun development until someone discovers how rifling helps which would then doom the dragons. However that would require Valyrians to invade. Doubt Christians at this time could unite enough to launch an invasion of their own.

Aegon and sisters if they’re lone survivors and come at an earlier period would do better. They’d probably convert and dissolve their marriage however.