If she is nine years old, there might not be much that you can do. Dogs get pretty set in their ways and she could have either been raised poorly or it could just be how she is.
If she is just protective over you, then she could just be so attached to you after you rescued her. She may not have had a friend like that in the past. You are now the biggest part of her life and she probably just wants to make sure you are safe.
If she is protective over the house, it is the same thing. She might just not be used to having a house like that yet. Some dogs are very possessive over new things.
If she is aggressive in general, that could be something from her past. For example, one of my rescues is weary around men, probably because it was a man that was abusing her or a man that put her in a bad situation. Dogs, especially rescue dogs are often not too good with strangers.
What I would do is have the same people over more than once to get her used to them. And if a new stranger is coming over, maybe introduce them outside or have them give her a treat or a toy to show her she can trust him or her.
It takes a while for a dog to completely get used to a new situation, sometimes much longer than two months. However, she is nine years old, so she might be set in her ways. If that is the case, it might just be best to keep her crated or separate her from the guests.