Hello, Rose! I love this question and I think it’s a great one. To clarify, before I give my thoughts, I’m neither deaf nor blind, but I have done a lot of research and I have a particular interest in Deaf culture and am enrolled to begin studying to be a sign language interpreter next year.
First of all, if you’re on any form of social media, look for deaf and blind advocates/educators on there! I use Instagram mainly and there’s heaps on there (i can give you some specific names if you want). These people have great tools, resources and just general info, as well as adding a personal aspect to things you might only read about in health articles, making it much more real.
To specifically address your question about the deaf mother, it definitely depends. You could try looking up the term “CODA”. It stands for Children of Deaf Adults, and there’s plenty of resources online, specifically YouTube, that talk about what it meant for them personally to be Hearing and yet having a Deaf parent/s. All of the things you mentioned are possibilities and I would just suggest doing some more research on each option, what it would entail for the mother, kids, other family, and then deciding which works better for your narrative. (here’s a link to an interview about being a hearing child with deaf parents https://www.hearinglikeme.com/being-a-hearing-child-of-deaf-parents/ )
Now onto Nesrin! She definitely could have gone blind from an illness or disease. Real world things like scarlet fever could cause blindness, but some other options are cataract, glaucoma, being cut or scratched on the eye and developing an infection, or head trauma and brain injury. She also could have been born blind.
Her navigation probably isn’t that much of an issue, if she’s adapted well to her blindness. The most common navigation aid for blind people are canes and this has been an aid for blind people for thousands of years. Heaps of blind people are able to live alone and with a great level of independence. However, also consider that she may not be 100% blind, as in unable to see anything at all. Many blind people are not “completely” blind and especially if she was suffering from a cataract, or head trauma, she would probably be able to see a little.
Anyway! That’s my thoughts! 😀 Sorry if I infodumped a little 🙂
Mahalo keia huiʻana