Tom took Leo's advice and got his mom a Chromebook, but she's still struggling with using it because of having to remember passwords. Leo says that some people just aren't wired for computers, especially older people, and it makes it harder to get comfortable with computers. It takes time.
Tom also tried using TrueCaller, which Leo says is crowd sourced spam filtering of voice calls. Leo likes the idea, but he's not really sure what's going on there. You do have to give them all your contacts, so if you're a privacy geek, that could be a concern. Facebook also has a program like that. Mr Number is another. The problem with these though, is that caller ID doesn't work. The number it shows is likely not real because of spoofing, and because a lot of companies block caller ID. So these programs can't help you there.
Google Voice is a good option though. Tom can just send the calls to voicemail there.