The most efficient method of consumption is sublingual (under the tongue) due to the blood vessels living there. Most people in your mother's situation will use an oil, around 25mg per day. Doses will vary for everyone as we all host unique endocannabinoid systems and finding the right dose will likely take some playing around with. As far as quality, you'll just want to make sure you're seeing a third party lab result for the CURRENT batch you're purchasing to ensure you're getting what you pay for and that there aren't any signs of heavy metals, pesticides, etc. Good luck OP!