This is more of a Windows thing.
If Windows senses anything has been changed on a particular network it may then change that network name by advancing a number even though no change has been made that you know of.
And this is not across the board, meaning 5 computers on the same network, 1 computer may change the network name while the other 4 remain the same.
I have 20+ workstations at my office and I may notice one of them saying connected to Network (6) while 2 may say connected to Network (2) and the rest being connected to Network.
You aren't being hacked I noticed this years ago on our computers whether they were on Windows XP, Vista or 7, even on the 1 workstation I have running Windows 10 Preview.
You should be able to change the name by Opening network and sharing center. View your active networks, put your cursor directly on the House, left click, change the name of your network
Also this has occurred on my networks before I used an Airport router and after.