I am happy that @PippaScope was able to assist you with some searching for UK suppliers of the Mouth stick Stylus, please do let us know how the product effectiveness and usability is with your mum.
With regards to eye tracker technology, I will be able to assist you further with this. Would you be looking at a head tracker, or a more specialist eye gaze tracking device? Both have similar results however the accuracy can differ, depending on the user`s needs and use of the device.
Suitability with GBS I presume you are talking in relation to "Group B Streptococcus" please correct me if I am wrong. The suitability will be dependant on the restrictions and difficulties that are present in your mum`s physical health.
Would you be able to provide me with further details regarding, physical limitations, and mobility from the shoulders and above. This will be crucial to understand whether the device may cause more pain or discomfort to current health problems.
I hope this helps and I look forward to hearing from you again soon.