How can we be sure the inheritance my wife and I have built up over the years to pass to our two daughters stays in our control and does not pass to the state?

I see you have several posts concerning your assets and going into some sort of care. Anything you give your daughters at this time can be "clawed back" for five years, meaning from the date you give the money until the date you need it has to be five years. If you turn your house over to them today, the same claw back applies. As for a will, the money left will be whatever is left after your bills have been paid, including AL or NH. A trust would have been the best option but I don't know about claw back there. Basically the government is not going to pay for anything as long as you have assets. You have to spend down those assets. They let you keep very little. It is the way things are done in the USA. You save all your life and it all goes to nursing care. So some good souls save alot and give it to nursing care, some give it away early so their kids can have something of theirs and some just never save anything. Sort of frustrating for many. Please talk to an attorney.

You need to create a will that spells out how you want your assets divided. There are also "living trusts" that are great for certain circumstances. If you transfer property to your daughters now, and need financial aid through Medicaid, there is a 5 year "look back" period. If you should need Medicaid assistance during those 5 years, Medicaid will consider those funds part of your assets.
I would not make any changes to your finances until you have spoken with an elder attorney or financial advisor. With all the cost increases in elder care, please make sure that you will always have enough assets for your care. (In my area, assisted living costs $3000./mo. and nursing home care is $8000./mo.)
good luck