My daughter receives a monthly check for my social security disability. She also received a separate 1099 from SSA. Do I include her SS income on my tax return or do I file a separate tax return for her?

That money is HER money; do NOT put it on your tax return, even if you claim her as a dependent.

More than likely, she will owe no taxes on her SSD income, because, by itself, it is not taxable.

It may become taxable if there are other taxable income sources in your daughter's name.