There are a lot of facts that have to be looked at here.  The timing of when C & D married, when C bought the house, and when C made her will, might be very important.  Depending on what, if anything, C left to D in her will, D may have the right to a share of C's estate (the total value of her property at death) that is larger than what the will says.  In some extreme cases, the will can be contested and thrown out.  There are other things that might be important as well.Even if the children are entitled to the house, removing D might not be as simple as changing the locks.D needs to see a lawyer who practices in wills and probate law, as soon as possible.  You can find one at http://attorneypages.com