Hi how old is your mother. You are describing features of what we call paranoia. This can happen due to many reasons e.g mental disorders, Medical problems or memory problems/ brain disorder. Please consult a Psychiatrist as priority. If mother suffers from physical health issues consult a physician
Next Steps
consult a Psychiatrist. she will need further investigation and treatment
Health Tips
try and reassure mother. take her to physician for physical health check up