Not sure how old your daughter is, but you might remind her that bullying has a way of bouncing back on them when they least expect it. Sometimes it doesn't throw much fear into them because they know the parents won't do anything anyhow, so why not do it? Or they're doing it to get the attention of the parents since they don't get it otherwise.
My daughter was bullied by a girl, who we both ended up talking to the dean at her middle school about, and the dean said she had a long history and the parents and child have been counseled before. Since the parents didn't take an active role to do anything about it, the child continued to bully and steal from other kids as well as took my child's cell phone and resold it, before we could get it returned. So, the actions only get worse if you don't do something about it.
Turns out that when we didn't see her in high school, there were some rumors she left town since she had such a bad history all around our area. Another was that she probably got sent to a different high school where they send the troubled students. But we're happy she no longer is with the kids she formerly traumatized. whatever the end result was, it ended up taking a toll on her whole family, I'm sure. So, if you don't take care of it now, you'll only end up paying for it later - or she will.
Another child started bullying my daughter and I had enough of it, so I sent her to martial arts training in case it came to a real fight. I didn't want my daughter beat senseless. The self-confidence alone gave her the courage to deal with the kids inthe future. It helped us that we advised the school as well, and told them to organize classes so that they weren't together. That, and the police record on the kid that we turned in, was enough to warn the single mom that we meant business. The bullying stopped there.
So, actions taken by you now will help you to avoid unpleasantries with other kids' parents and a potential record (school or police) on your daughter. At some point, another patent will step in and do this if you don't take action - if they don't, kids will only take so much before they break, and do something drastic themselves to take care of the situation. I didn't want that to happen, so I stepped in myself to take care of it.
so, not sure if this really answers the question of how to handle it. But I can speak from the other side that you need to handle it - before someone gets seriously hurt.
This may be the obvious solution you've already tried, and it will only help certain kids, but why don't you take her with you to help take care of your mom. Maybe if she can see the work and frustrations and stress you're dealing with, she'll realize that the bullying is only creating more for you to handle. You may not want her to see that, but sometimes kids have a lot of insight on their own, and will adjust behaviors accordingly. If she's a little older, you might even ask her to help. Then, you can tell her the best way to help is to be good so you can deal with the other things with less stress.