Secret of Mana

You could try leveling, or if you're really good equip the hero with the bow so you can hit Spikey Tiger on top of his pillars, it is a tough fight with the hero alone though.

You have a few options:

1. Head back to Neko in the prison cells where the solders were captured and purchase a cup of wishes or two. These instantly revive a character to full hp. If you don't have enough money either fight carefully with the hero to get it or...

2. If you are really in trouble you can always try fleeing the dungeon. I don't remember if the magic rope works here or not, but it will at least get you outside the castle. From there just run through the woods dodging all the enemies. If the magic rope doesn't work then...

3. Do just like I mentioned above, but run through everything including the witch's castle. Run through the woods all the way back to the warp out and head back to either the Dwarf Village or Kippo Village south of Gaia's Navel. Then a simple sleep in an inn will bring everyone back to 100%. This should be no trouble to do, since you won't have your allies constantly stopping to try and attack enemies. You dash with the A button will be useful in getting past tricky enemies quickly.

Buying cups of wishes from neko works but if u are in real trouble just attack alot use charge attacks and mos important WATCH YOUR HEALTH !