I'm going to be honest here and I hope it doesn't upset you, there is no blame or judgement, just my thoughts on what you have said. She sounds like a scared, confused little dog. One of the house moves seems to have upset you and her, I'm not sure I believe in ghosts, but it seems something was going on. And it's likely the moves after haven't helped her feel safe.
I also think she is a very very lucky dog to have a family that are so willing and ready to stick by her. The only time I would suggest giving her up is if you and your family weren't willing or able to put in the time and training/work she requires to make her happy again. And even then it would have to be to someone who could give her what she needed. A lot of rescue centres just don't have the time or resources to give to a dog like this and would have her PTS as rehoming would be deemed too dangerous (not all rehoming centres are like this, but a lot are).
Timber is right, you need to go back to basics. A house line (a very light, long lead) is a great way to reduce stress when you need her to move at any point (off furniture, into another room ect). My method would be for everyone to have a pocket full of treats all the time, if you need her to move or come to you stand at least a few feet away, with nothing blocking her path and ask her to go where you want her to, and gently toss a treat that direction. If she goes the right way tell her she's a clever girl in a happy but calm voice (not giddy!) and gently toss her another treat. If she doesn't go pick up the house line, ask her again to move, use gestures, walk that way and gently guide her with the line, don't drag, you want her to follow and not struggle. It might seem like a bribe but it is the basics of lure training. So for example you might need her to move so you can get comfortable in bed, give her room to get off the bed if she feels uncomfortable, don't touch her in anyway, toss a treat where you want her to go and give her to the count of 10 (in your head slowly) without out staring at her to move. If she doesn't move gently use the house line (lead) to encourage her to move. Hopefully if the treats are tasty enough she will move easily. Once she has moved toss her another treat (gently toss it near her, don't lean in to feed her by hand).
Another exercise that would be good to do is to have lots of little treats, be in the middle of an open room (no clutter, lots of room for her to move away if she wants), sit sideways to her and call her to you, using a happy voice, but nothing to excitable or dull. If she looks your way or comes closer tell her she's a clever girl, look away and drop a treat to the side of you that is closest to her. Once she takes the treat, calmly tell her she's good and toss one a few feet away so she has to walk off to get it and repeat. Don't touch her or stare at her.
Once she is great at that we know she doesn't think you are a threat, she might be fine the first time, but do it a few times a day for a week or two then we know she has gained some confidence and trust that she isn't going to be forced to do things.
Next I would work on touch, lots of treats, still in the open room, this time touch her in her favourite place. My dog loves his back being scratched, or his chest. Give her a treat. Move somewhere near this preferred area and give her a treat. You are going to slowly work over time to get her to accept one hand anywhere on her body, go at her pace. If she backs off, bites, growls, freezes or cowers you have gone too far too fast, back up and try again starting at her favourite place. This may take days or weeks. Then two hands, using the same method. Touch treat, touch treat. Then rubbing with one hand, then two. This is all about her learning that hands aren't scary, and with hands comes good things, treats and rubs.
As for visitors, for the time being keep her locked away in another room. I'd give her a kong or similar toy filled with yummy food to keep her occupied and calm and make it a positive experience. Once she is better around you and your family, you can work on having her near visitors using a dog gate, having her at one side and give her her kong before someone comes over. Have them completely ignore her. Once they have gone leave her in there for another 10 mins or so, we want her to think she just happens to be in there and it's a good place to be (kong/food). Let her out as long as she is relaxed and calm and pretend nothing ever happened.
If she has something she wants then you can't have it. Try swapping it for something else, so a pile of treats a few feet away, so she walks away from what you want back. Try to not get in the situation where you have to take things from her, bones should be fed separately. I'm not sure what else she is guarding but you need to decided can she keep it, or are we going to lure her away with something even better than what she has. Once she isn't as nervous and ready to bite you can work on a leave it command, for now I wouldn't go near her when she has something of value. I don't want anyone hovering over me or touching me while I'm eating my favourite ice cream, I'd be liable to telling you where to go too, and that's just what she is doing.
With the beds, if she can't get up and down by herself then I wouldn't let her up. It's too dangerous right now for anyone, never mind 12 year olds to be lifting her. It's not helping her and it's not helping them. Also once she has completed each exercise and is 100% with you, you can help your family do each one with her, so she can learn to trust you all again.
Last thing, I promise, all these treats will make her fat, make sure to give her a bit less food at meal times and lots of exercise to counteract the extra calories. While my dog was doing lots of training he didn't eat out of a bowl, he was very food orientated and I just used his normal food but put it in a bag with some cheese and cut up hot dogs so they smelt extra yummy.