UPDATE: I updated my game to 1.6.353 then used the downgrade patcher, found on Nexus. And everything works now. I appreciate DoubleYou for looking at other possibilities.
Thank you for looking. I noticed the hall is not on fire and the bodies are missing outside too. Cannot get in the hall. Like to verify files, but I am still SE. There is something that is either effecting that area, or the start of the quest. When I walk through the side of the mountain the quest continues like normal. Have a great day!!
Just saw your post. Thanks for telling me about this mod. This is something I actually would use. I am whipped tonight, will have to get those tomorrow. Thanks for the help you have given so far.
xedit showed a conflict there with Majestic Mountains, which I have ran for ages with no troubles. I reloaded MM but no change. I suspect some sort of landscape fix, or patch. It has been a while since I started the Dawnguard quest, so hard saying when it happened. Haven't ran across any other caves covered up. So, it appears to be just the Dawnguard dlc. I went ahead and got Serana, Everything seems to be working fine. I will play around with it later.