Thank you for the additional information.
There are a few possible causes for mucus stool that contains blood.
*Eating something new that has upset the digestive tract
* Intestinal parasites not just worms but microscopic parasites as well such as coccidia and giardia.
Here is more on parasites
*Colitis and IBD
* Bacterial or fungal infection
* A more serious problem would be a condition called HGE this normally produces large amounts of bloody jelly like stool or just straight blood. With this problem the dogs is normally acting ill, That said this can develop very quickly so you want to keep an eye out for any additional problem like vomiting blood
Here is more on this
As long as she is eating and otherwise acting normal it would be ok to watch her for the next 24 hours.
I would feed a bland diet for the next 48 hours of boiled chicken and rice. This is easily digested and the rice will help with the stool.You can use pieces of chicken for treats but no dog treats for 24 hours
If the diarrhea continues longer then 24 hours, she stops eating or begins vomiting I would have her seen by the vet and have the stool tested for parasites.
I hope all goes well, please reply back if you have additional questions or concerns