You need to think of the trust and the estate as two different "people". The estate's assets, those things in grandma's name and ownership, are distributed by the executor according to intestate succession or will by a process called probate. The assets owned by the trust are distributed by the trustee according to the terms of the trust. A trust does not go through probate per se. (Although certain trust assets can be used by the estate to pay creditors.)
Since the trustee has died, there needs to be a transfer of legal (not equitable) ownership to the successor trustee. The trust should name who/what this is. Most good trusts will list another trusted person as a successor trustee and can list others as well--it will then list a probably long-lasting institution (like a bank) to make sure there will always be someone who can be the trustee. If not, you have an even more difficult problem at hand. You need to get a copy of the trust and find out the successor trustee to initiate proceedings to become trustee because of the death of your uncle. If you are not the named successor trustee, you cannot do anything at this time. Once this transfer takes place, the new trustee can distribute from the trust according to the trust documents. It is unlikely the documents will allow the trust to pay costs of the estate--but it may.
The estate will need to be opened in probate. If it has not been opened yet, you can do this yourself by petitioning the court. If named executor, you can pay funeral expenses from the estate and deal with the property appropriately. (You will need permission from the court to do certain things.) If the estate was already opened years ago by uncle, it is very likely the estate was closed. I would have to look things up to find the process to appoint a new executor in a closed estate, but it would require a new motion of some sort. Then, a motion would be needed to reopen the estate and then a motion to add the property of the house to it.
Even talking to the bank to explain the situation may be difficult because of privacy issues in the hope they will, rather than foreclose, negatively amortize the loan until control of the property is had and a sale can be made.
If you have a reason to believe the house should be in the trust, and can prove it, I might try to get a trustee of the trust. Then, have the trustee try to petition the house into the trust. But that's because it would be easier. While often done, it is not routinely granted, even if you have good proof of intent, depending on the court.
