Question: how do I connect to each other with lan without data or internet on minecraft pocket edition can I use Bluetooth or is there any bugs?

Answer: 
A lan can be many things, multiple devices on a router for example.
But lan is more defined as computing devices that communicate.

You can achieve this by connecting two computers with a lan cable, no router required.

You can make a lan using Bluetooth, or just a phone hotspot.

You can even make a lan using one pc. You can run a program that runs two separate versions of 64bit Windows that can communicate to eachothers and render it in split screen. 
(Similar but not quite what console split screen does) 

All from the same pc...

This guy, In the comments, you can tell he doesn't know what he's doing.
The devices need some means of communication, they are not magic.
The comment was not well worded but I did my best to decipher your text.
If it's a Xbox you are going to want to connect to her phone's hotspot. 

She will by default have the same ip, because your just a extention of her phone's data.

I am not sure how it works on Xbox, but Xbox might require you to login.
I'm sorry but on version 1.9 (beta, even when paid) you can't play offline multiplayer anymore... I tried it with my friend updating her ap to this version and I can't get the local server from her phone and when I go to worlds tab > edit world > multiplayer it was enabled but when I play the same time I go to the settings I can't toggle back on... Now I have to connect to internet and sign in my xbox live account...