my g/friends father is in a v/a hospital and his other daughter is selling off his belongings and putting his home up for sale before he passes away

You can't challenge the will until after he passes, but you can challenge the authority by which the daughter is selling everything now.  Why is she doing that?  Does he need money for his care?   Does she have a Power of Attorney that allows her to sell real estate?  Where will she keep the proceeds from the sale?  these are all questions that you have the right to know the answers to and can demand those answers from the daughter who is selling assets.  If she does have a Power of Attorney, you have the right to demand an accounting and should do that in writing, certified mail.  also get a copy of the POA and if there is no POA then find out how the daughter is liquidating things.