My 90 year old grandmother lives in a retirement apartment. She goes out to walk all the time, and frequently crosses a busy street to get an ice cream cone at McDonald's. She's independent in her ADLs and is absolutely allowed to leave the facility at will. Just the other day, someone stopped to offer her a ride, and boy was she insulted!! I tried to explain that someone was just trying to be nice to an old lady, but she was having none of it. It was nice of you to stop, but if she refused your help and didn't seem confused, I don't think you are obligated to pursue it further.