@Jack Ni, I'm no arborist but I share @Brian Van Pelt's sentiments. Based solely on your description and the photos, you might be worrying about this too much. First, as you point out, the trees are your neighbor's--and, thus, their fate is ultimately his or her decision rather than your own. That's not to say you couldn't talk with him or her, but it's worth carefully considering the validity of your concerns before you do.
Second, if only the upper branches would come in contact with your property if the tree(s) fell directly on your home, the damage would not be nearly as catastrophic as if the trees were closer, causing more of each tree's trunk and weight/force to come in contact with your home. That's not to say they can't cause damage, but it's highly unlikely to jeopardize your tenant's life while in the home.
If the trees were clearly diseased or had a dangerous lean, there might be greater cause for concern, but this does not seem to be the issue here.
To put your mind at ease, consider taking a drive through some other neighborhoods near your property. I imagine you'll find many trees far closer to homes and capable of doing far more damage than your neighbor's trees. If anything, your neighbor's trees are helping enhance the value of your property by making the area beautiful, providing shade and protection from the wind, and providing valuable habitat for birds and other animals.