I'm a total choice fanatic. Rather than make up a specific plan that you recommend to her, I would make her a short list of improvements and then she can choose which one or two to implement or if she wants to come up with an idea of her own to begin with. As much as she says she wants your help and as much as you sincerely want to help, all lasting success that she has will come from within.
As a side note, I'm slightly concerned that your mother-daughter relationship could be affected negatively if you get too involved in her process. I think there are lots of folks here with significant others and parents *involved* with their weight loss who can tell you how emotionally complicated that can become... I'm not saying don't help her, just something to be thoughtful about.
I am a fan of
3 meals + 1-2 snacks daily,
reducing processed foods (if I had to pick one to eliminate first it would be to eat nothing which contains corn syrup)
allowing unlimited fruits and veggies,
multiple short walks each day. And short can be SHORT. If 10 minutes is too long 5 or even 2 will do to begin. Just begin the habit and be kind to the joints.
Increase water intake.
Get plenty of sleep and if a snorer get a sleep study.
And show her this website!!! Finding this website, relating to others' stories, feeling understood, receiving encouragement which comes from a place of empathy, and the freedom to say things that cannot be said in other venues: priceless beyond words.
Congrats on your own weight loss and cheers to your continued improved health and giant kudos for being an example and encouragement for your mum!