My mother-in-law has a will that states all personal property, including house & cars, be left to my husband. If he sells the house or other items, will he need to share the profit with his sisters?

So in other words, the mother is excluding them from her inheritance and forgiving their debt to her as their part of the inheritance. Putting it that way makes more sense, to me at least.
So unless they were expecting her to die and NOT have to pay her off, PLUS get more money on top of that, then there could still be trouble for your husband. But that's not his fault, and though he can be sympathetic to their cause, they already spent their inheritance right? Sticky wicket we have here.

Thank You yes, she may have had good reasons they (the sisters all owed her lots of money) but the will states if he (my Husband dies) then it goes to the younger sister, if she dies, then the next sister etc.. does that make sense to you?

Oh man, what a recipe for disaster if your husband keeps everything. Unless his mother had a really good reason for excluding her daughters, then I would think it would be wise on his part (if he ever wants to see his sisters again) to share the wealth. Why would she ever put your husband in that position in the first place I wonder? hmmmm