There a number of reasons your mom could have "passed out." Only a physician will be able to determine that. Please call your mother's MD, if she is unable to do so. If it happens again before a visit to the doctor a call to 911 would be most appropriate.
Take care.
She passed out on the toilet and fell to the floor? She needs to go to the doctor. As Ann Landers used to say, show her this post. Her issue can 't be diagnosed from here. Maybe it's just that she has an especially horrible stomach virus, and she will get over it, but better safe than sorry.