How best to protect parents' home from Federal & NYS estate & inheritance taxes?

Parents are in mid-80s with cancer. They have a will which does not yet include their home. Is it best to put home in names of 4 children now or will "look back" law apply & if so is it 5 years look back? Parents may or may not survive 5 yrs. What is best option for asset protection to retain greatest net inheritance? I am executor & parents wish is to leave maximum net to 4 children. Should one or both become too disabled to live independantly, they will live with me & home will be sold (unless not best solution?). They previously took their one-time sold home capital gains deduction 24 yrs ago. Current value in NYState has lost 10-20 % market value but is still worth approx 100, 000 more than original purchase. If one parent survives other, remaining parent may stay in home if health allows. Best way to proceed, given these senarios? Thank you so much for options & advice.