Bed wetter =(

Awww my first question would be, does she fully eliminate prior to her bed time.
Next would be a concern, if she is elimanting normally during the day, and prior to bed, I would have her checked by the vet. Is she taking in more water then normal, has Mom noticed a difference?

First is a vet visit. Incontinence is not normal and should always be evaluated by a veterinarian.

I've had two females over the years that had this 'sleep incontinence' after spaying though it didn't happen immediately. They were fine when awake and would let me know when they had to 'go" but during nap or overnight they'd be in deep sleep and go and not be aware.

It's a common disorder with spayed females where the spincter ( little valve that holds urine till they feel the need to go) becomes 'lazy' for want of a better word. I was given a medication that took care of the problem in a couple of weeks and it never returned. I have, however, read that some need it longer and in some cases hormone replacement might be needed but in all cases I know personally I don't recall any needing this.

You need to discuss this with you vet and be sure to rule out any other possible heath issues as well.

Wow ,never heard of that in a young dog but Amy our cocker had that as she got older,about 12 yrs old. Vet gave her meds and it all but didappeared in a day or two but she was on meds for it until she passed.