ASAP. My mom's friend's son and daughter in law wants to move in for 2 months.?

My mom's friend who I called Aunt for my whole life, has a down on his lucky son who's wife I met while help caring for my so called aunt. They want to stay with me for 2 months, and willing and able to give $200 a month. Here is my question, $200 will not make or break me. It can give me a little breathing room, but not much. I was going to let them stay for free, but the wife insisted. If I accept the $200 does that mean if they try tio stay longer, would I have to go the 2 month route to evict them, after 2 months I am willing to let them stay. The wife seems like a responsible person, and I do not feel she would screw me. But my aunt's daughter talked me into buying a condo, and assured me we are in it together. Just tio be sure I had a contract made out explainning what we agreed to on the condo. She made excuses why she had not signned it, and I ended up eating 25,000. I am willing not to assume the son, and wife of my friend aunt trust worthy and not like his sister. But I want to protect myself. I am thinking not to accept the $200 so I do not have to evict them, when and if I do not want them in my house anymore. I think If I want them gone they have to leave, that day, if it is not working out. Am I right?