Hello !
Immunity depends on many factors like good sleep, low stress, medication, food intake and light physical exercises.
Your mother should take 3 litres of water daily , fresh fruits and raw vegetables, lemon water, turmeric milk , ,10 minutes of sunlight exposure, good sleep and 20 minutes of yoga everyday can help keep her immunity at optimum levels.
The best way to prevent any covid exposure or infection is to stay indoors , wear a mask to step out only if essential, wash hands regularly. This is very important - specially for people with previous breathing issues.
Next Steps
Consult on practo for further advice
Health Tips
Avoid stepping out , do not take any medication or supplement without expert advice or prescription