If you sent the declaration letters from any non-taxable pension, including the one from Social Security, you should have all the income evidence you need. If her total annual payments from the pensions and SS are well above the minimum, yes, I would expect no issues with the public charge judgement call, unless the retiree is of a very advanced age. "Elderly" sponsors are not always the best choice, but it will be the totality of circumstances that carry the day, or not.