Im renting my uncles home, and he moved someone else in. I installed cameras for security with his permission. I also installed one in the living room, that's watching the front door. So the person that's renting the attic sasys she can sue for invasion of privacy. Can she?

No... the front door is NOT an area they are renting. Its no different than a camera that is in a lobby of an apartment builting or condo pointed at a common entry point... as long as its not inside the room they are renting (attic in this case). Or an area where privacy is expected such as the bathroom.