My daughter whacked her foot last night and tore skin and has a bad bruise. Do I need to take her in to the doctor?

Notify Dr office/nur. The question is how bad is the skin tear or if she has a fracture or just sprain? If the tear looks deep it is better to see a dr for possible stitches not six hours after rhe accident, for wound care and possible tetanus vaccine. If the pain in the bruise area is significant she might need x rays otherwise, cleaning the wound, covering it, some elastic support or immobilization of the area:ok.
Wait... Give it a few days to see how it heals. Keep the abrasion clean and covered for a few days. Look for excessive redness, swelling or streaking. If that occurs, I would see your doctor or Podiatrist.