Legal Question regarding real estate in NY?

My mother nearly ped away yesterday. Her health is deteriorating rapidly. Both my mother and I own a home which was left to us by my father who ped away. Basically 50/50 both our names on the deed. My mother has 2 daughters from another marriage and has no will. If she ped could her two daughters claim her 50%. Do I get part of her 50% even if I already own 50%? If the judge gave them 33% each or 25% if only one of them sued would they be liable for the bills and expenses that the home needs to cover as well? Should I try to convince her to leave a will and leave me sole heir of her 50% of the home?