Hi. Your mother seems to have a sensorineural
hearing loss due to ageing which is also known as
presbycusis.
It is the ageing of the auditory nerve, making it weak and inefficient in picking up high frequency sounds especially those that are perceived over a telephone or while watching TV. Nerve related
deafness also leads to lack of clarity of sound and it is understandable why your mother is unable to differentiate between some similar sounding words.
Unfortunately, the best treatment for this available in the market is a good quality
hearing aid which will amplify only the sounds she is unable to hear and improve clarity of sound. But since you do not prefer them, the only medical management would be with
multivitamin supplements.
I would recommend multivitamin supplements (which include vitamin B complex with
methylcobalamin and other trace elements) once daily after meals. These supplements improve the wellbeing of the nerve to some extent. They may not be able to reverse the age related
nerve damage and bring her hearing back to normal, but may prevent further ageing of the nerves. These multivitamins may be taken for the rest of her life.
In addition, it would be recommended to avoid further exposure of loud noises to her.
Hope this helps. Do let me know if you need any other information.