Why is my client feeling like she and her husband have spirit attachments? Why are they afraid being in their home, hearing voices, noises, footsteps, and seeing shadows out of the corner of the eye? Why is her dog acting quite fearful?

As you saw intuitively, there is a deeply troubled lost soul human spirit on the premises. It is working to get their attention and it is wanting them gone. She is sensing the negativity of this being, primarily. There are other dark spirits involved as attachments as well, and they are egging this spirit on and using it as a kind of agent provocateur to cause inner turmoil and fear, as it serves them to have the humans perturbed and creating more negative energy for them to use. This will be a good exercise for you in doing a series of Protocol sessions for this family grouping. It will strengthen them and add further protection, as well as initiate some karmic repair which, as you know, is always of benefit and will get things going so that they can be free of this dark entity once and for all.