It appears the Mobility Allowance cut applies to all people in 'residential care'. This is a major cut, £20 or £40 odd pounds a week per person. Lots of disabled people will lose their Motability adapted vehicles, some people use this for motorised wheelchairs as they can't self propel. One distressing aspect of this is that it was referred to briefly in George Osbornes statement - a passing comment referring to 'equalisation' which was only elaborated as a cut to Mobility Allowance about page 50 of the Treasury statement.
My request to write to MPs was not on my own son's behalf, though it does affect him. It was to stop this being enacted for all disabled people getting Mobility Allowance in 'residential care' - this is a standard care model for many disabled people living in the community - particularly multiply disabled, people with complex care needs and learning disabilities. These people often get only £20 a week 'spending money' because their care is paid for. Mobility Allowance allows them some independence - until this takes effect.