Each of my wives lives in a house in my name. How do I make sure none of them loses her home when I die?

Plan while you are alive, because after your death each of those houses becomes part of the estate shared by all the heirs. Without planning, the first wife may be entitled to part of the second wife's house, and vice versa, and both could lose their shelter. One way is to gift (hibah) the house each wife lives in to her while you are in good health, with a complete handover. Make sure their values are not too different, or explain the reason for the difference. If part of a house was paid for by the wife herself, record that contribution. All of this must be done openly with all your wives, not quietly. Get advice from a Syariah lawyer so every document is valid and hard to dispute. See a husband's responsibilities.