How Do I Fix My Mom’s Phone with Constant Ads?

Since the ads are appearing on the home screen, check if the Android launcher has changed. Sometimes a rogue app can switch it up without your knowledge. Look for an app with 'launcher' in the name, such as 'Nova Launcher', and see if it’s been altered.

Honestly, I would just factory reset the phone and start fresh. It's the quickest way to fix major issues like this.

It’s pretty rare for phones to get viruses like computers do. Usually, if there are constant ads, it’s more likely that a website or app has permission to push notifications. Without knowing more about how and where the ads are showing up, it’s tough to give solid advice. I suggest backing up all important data like images and contacts, then doing a factory reset. If there's a memory card in the phone, consider reformatting that too.

It could be that a fake version of an app was installed. Check with your mom if she installed anything new recently, and consider uninstalling any unfamiliar apps.