First we need to know the status of your mother, is she a "tax resident" in Canada? If yes, is she just visiting and will eventually return home, or is she a PR? Also what will happen to the money if she needs to return home after her stay? The tax implications are different depending on the status of your mother.
In general, say, she is visiting, and she's got a bank account with one major Canadian bank, then she's considered a resident for tax purpose. And the interest income is subject to tax, but since she gets over $8000 exempt quota too, it's technically tax free. In this case, it's better Not to invest the money in your name. Don't think you can avoid tax if you move the money into your kid's name either, as all interest income is taxed under the guardian, which is you.
If she needs to go home after her stay, then her status will change, and whatever she has in Canada the interest income is subject to a 20% tax, the same as the tax rate in China.
If your mother is a PR, that's a different story, and need to take all other factors into consideration, her CPP/GIS/pension if any.
Just my two cents.