What can I do about the fact that my dad's wife is isolating him from the family?

I do not profess to understand your situation fully, however, nothing comes between a child and his/her parent's relationship. This has to be said by your father to his wife. Is he afraid of her? I agree with the rest, if the situation is not condusive to see your father at his home, than you have to ask him to meet you outside and he prepared whatever his answer maybe. I wish you all the best.
God bless

I agree with the above posters..Meet with your father in a neutral location and tell him how you feel.

Call him or contact him when she's not around and ask him to meet with you in a restaurant, park, cafe or library. It's important that you get together with him. There's not much you can do about her rules that prevent you from coming to "their" house. This is a sad situation. You can deal with it however. Good Luck.

Please explain this situation in a little more detail. It is my opinion that you must see your father as often as possible. For his sake, calm and harmony must prevail. Where there is a will, there is a way. FIND it! Good luck, Sooz

What is going on with your dad's health?

Is the house in only her name? If it is in both names, she has not right to keep you out of their house in my opinion.

Can you and your dad visit away from the house without her so you two can talk about this?