Was your father a beneficiary of your grandmother's trust? Was he allowed to receive the house outright or was it left in Trust for your father's benefit? This makes a big difference. If you father was either an outright beneficiary of the house or if he had a right to distribute the house to himself, then you would have a right to some portion of the home as an heir-at-law of your father. If your father was required to keep the home in the Trust, then the beneficiaries of the Trust would have a right to obtain the house by claiming that your father breaches the Trust terms by transferring the house out to himself. However, they would have to make that claim against your father's estate and they would only have one year in which to do so.
In the end, it depends on what the trust says and what the successor beneficiaries of the Trust do to try to obtain the house. You definitely should sit down with a lawyer to review the documents on this one.
Whether or not a Trustee 'agrees with' them, the dispositive provisions of the Trust are what he or she has a fiduciary duty to follow, like it or not. It's hard to fully answer your question without looking at the actual documents. Sit down with an Estate Planning attorney. See Avvo.com under Find-A-Lawyer. Take what documents you have and discuss the best path going forward. Good Luck.
It really wasn't up to your father to decide whether he "agrees with the terms of the trust." One of the original purposes of the trust was to dispose of the property according to your grandmother's wishes. Your claim to the property probably depends on the terms of your grandmother's trust. If it provided that your father was to inherit the house at her death, then the transfer from the trust to your father may be valid. In that case, if your father subsequently died without a will or trust, you may stand to inherit the property (or a portion of it if your father was married or had other children). Regardless, you should attempt to locate the applicable documents and make an appointment to meet with an estate planning attorney to review them. It is likely the terms of your grandmother's trust will hold the answers to this question, thought you may be unable to obtain a copy.