Invest in a local architect that will design an addition with you that meets your family's needs (now and in the future) and fits the site. Existing conditions will greatly influence the design and that critical information is impossible to communicate over the internet.

Does the space have to be 30x30? Often, longer and narrower will provide a more functional space. I can't make heads or tails of the drawing and pics you posted. I agree with Mark that a local architect could better advise you based on the existing structure, elevations as a whole, and site information.

Thank you. I've contacted someone. Hopefully they'll be able to help me.

Make sure they know barrier free design, have residential additions experience, and are licensed.

He works with the best contractors locally.  I've seen some houses he's designed and some the contractor's have built on his designs. They flow very well and are very nice additions to existing homes. He's very busy but will help us.  We close on our loan Aug 8th. So we need to know if we'll need more funds in the next couple weeks. Stressing...

But does he know barrier free design and is he licensed. The more competent he is, the less stress you should have.

Is the green house your house, or is that the addition? What's the cedar building? Is that your current floor plan or is that what you want to do for your mom? It's really not clear what is what!

Softener he's so busy with selling his friend's estate he can't come out here. He wants to do everything with photos of interior and exterior of the existing cabin (green) I'm very disappointed and afraid.

Apparently, not softener..

Sorry folks and thank you for trying to help. I'll just work with the contractor since this guy doesn't have time for me. This stinks.

Continue looking for a local architect to help design the addition. Keep enlarging your search area until you find a good fit.

You have another option for ideas, and a good contractor can help get you to the finish line. https://www.architecturaldesigns.com/house-plans/400-square-foot-one-bedroom-cottage-560009tcd

Set the filter for 1 bedroom, 1 bathroom, 1 floor, and scroll through the ideas. I bet you find one you like.

If I were Mom, I wouldn't like my bed out in the open where friends might drop by, but I would like a bistro table and chairs in my room if I were bedridden. And a nice view would be nice, but not too open, because I get afraid of the dark as I age. 

If I were Mom, I would want my bed so far from the toilet.

If I were you, I'd want a small kitchenette to heat and refrigerate leftovers. A small laundry closet might come in handy.

Look at the designs and see what could work and what you like. Then, see what your contractor thinks. See what Mom thinks. Run it past us if you want. 

Tell us more about Mom's condition and long term plans.

Sorry... wouldn't... want my bed so far from the toilet. And you might want a wet room bathroom. Go to a local nursing home and ask to see one in their skilled nursing section. 

And, depending on Mom... might want an outdoor space, somewhere to sit and have some fresh air. Sometimes shade will be nice, but other times some sun would be good for Mom. If I were Mom, fresh air would be important.