What should i do now?

Maybe she's worried that she'll become less independent with you visiting her and doing so much or her. I bet she's just worried that she doesnt want to become the sort of old person who people see as a "burden" I think maybe she wants to know that you like visiting her and that yu dont think she's a burden to you. Maybe phone her once more and just ask whether she wants you to keep coming to see her, i think she wud have to be honest with you then.