Julie Sayles, 59, of Sewerby Road, Bridlington is alleged to have persuaded Edith Negus to change her will to benefit her.
She also bought two houses with money she allegedly took from a joint bank account she shared with Mrs Negus.
Ms Sayles, who worked for an elderly-care charity, denies fraud charges.
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At Hull Crown Court Ms Sayles described herself "as a woman of faith".
She said she became close to Mrs Negus after she started taking her for days out and church visits and said Mrs Negus was not getting any support from her family.
Ms Sayles said Mrs Negus had known exactly what she wanted to do with her money and that she "had repeatedly said that she wanted me to have that money".
Prosecutor Robert Stevenson accused Ms Sayles of "being a liar" and said she was taking advantage of the fact Mrs Negus was no longer here.
Mr Stevenson then asked Ms Sayles why she did not inform Mrs Negus's family about the will change. He said that if she had contacted the family "her game would've been up."
Ms Sayles denied the accusation and said that the family had the opportunity to discuss it with Ms Negus and contacting them would have meant she would "have lost her friendship with Edith".
Ms Sayles is accused of fraud by abuse of position, buying properties with the proceeds of crime, making a fraudulent will and presenting it to a solicitor.
The trial continues.
A carer accused of stealing almost £290,000 from a 102-year-old said the woman "wanted her to have the money", a court has heard.