she is self employed she has child care checks and personal checks from parents as she owns a day care so what should she show

Document it with recent bank statements showing that she is regularly depositing money (parent's checks) in her account, make copies of the checks she receives from parents (if possible), copy of her business license or child care license. Also, if possible, copies of contracts (or letters) from her customers (the parents) stating how much they pay her each month and copies of ads or other printed materials she has about the business. Basically you have to show she has a real going business and has the income she claims. Of course, she has to have declared it on her tax return for last year. Making "cash" but not paying taxes on it does not count (and is illegal).

No there is no Cash just checks and they are all declared on her tax returns

Great. Then you shouldn't have a problem as long as you document it (see my answer above).