It usually takes longer to get them 100% potty trained when we work or are not home 24/7 where you can really focus on the training and not allow them to have accidents.
She was used to being able to go out when your mother was coming over, now she is alone for a long period of time and probably isn't used to holding it. Most dogs (and people) can hold it longer when they are sleeping, just because you aren't moving around.
Please don't think she is "doing it on purpose" Dogs are not spiteful, as much as we might want to think that at times
especially when it comes to potty. But she is not just trying to "show you". If she is going a lot more than normal, you should really rule out any medical reason before anything.
Also, at 9 months, probably not a good idea to have her run of the house when you are gone. Can you gate her off in a kitchen, or tiled room, with an expen, or crate and pads?