My daughter is 10 and got brown scabs over and around her nose and same all across top lip, blister on right cheek can light treatment cause this?

It could: This could happen after light therapy in the form of a burn.

Another thought: If the scabbed lesions you are describing have surounding redness, are warm to the touch or have pus-like secretions then impetigo must be considered. (a superinfection after uv tx and skin breakdown) this is a strep skin infection most common in younger patients. Typically, these scabs have a yellowish, honey-like appearance. If so, see you doctor immediately. This infxn can be tx'ed with a rx.