Around here, PG&E regularly trims tree branches and limbs that could interfere with high voltage lines. They contract with professionals to do the work. I must say that just recently, there has been some very unprofessional looking work done, and some trees have a huge V-shaped void cut into their canopy. It looks hideous, but usually they take a more surgical approach.
We had a lemon-scented gum at our other house that was getting into lower voltage wires and our tree guy wouldn't go near that job. I would think that in the interest of avoiding a power failure, for your situation the utility would do the necessary work to remove troublesome limbs and branches, but only where high voltage lines are involved. If the tree is only interfering with lines that serve your place and your aunt's, then they likely will not take responsibility.
Regardless, tree work is not cheap. Around here, removing a tree of that size could easily approach $5,000 depending on what the market will bear in a particular area.
Lawrence, I just clicked on your checkmark. I take issue with our mysterious Palm Springs newbie. I'd wager she'd not only read it, but also wouldn't be able to resist posting a scathing "I told you so" should a thread describing a worst case scenario appear here at some point in the future.