.. just a thought... but this is not really a "basement apartment" because there is no kitchen.
however, the is the issue of "Means of Egress"..... it must not involve entering another dwelling unit or occupancy, and must lead directly outside at ground level.
You could get away with installing a good egress window in the basement. They do exist....
One egress is allowed if the house is sprinklered.
Also, you should have interconnected smoke alarms. If the upstairs goes off, the basement ones go off too... and vice versa....
I wouldn't really rent the basement unless there was a side door.