I applied visitor visa for my parents and it got refused. I have attached the refusal letter.what can I do. Need help

Question

I am the financial source which mentioned in the refusal letter . I provide my parents 50 pounds each month which reflects in my account.i am planning to provide my bank statement also. Secondly , I am planning to attach letter from my father's brother and his family and his mother. The land and house is in my name . So I am not sure whether I can attach that . In there they have only car and gold of around 50 pawnas. So shall I do a valuation by chartered accountant about the car and gold. Please suggest isbthis alright. I am the complete sponsor in uk as a daughter. I money in my parents account shows various cash amounts is that she pledged her some gold and put som money in her account . I am planning to attach the receipt of gold loan and statement of that bank. Need help