What can I do if my Mom who had 4 adult children. And one of them decided to change the deeds on my mother property while she’s incapacitated in hosp

This can only be done, and then in line with your mother's Will or, if she has not Will, distributing to her heirs at law, by someone who is her agent under a Durable Power of Attorney recorded in the county deed records or by someone who has been appointed guardian of her estate by a court.  If your sister is neither of these, you might want to talk with an elder lawyer about getting the apparent fraud undone.  You can find one near you on the website of the National Academy of Elder Law Attorneys (www.naela.org)