Can a Bank Foreclose on Deceased Mom's House?

Can bank foreclose on deceased moms house even though the mortgage payments have been kept current? The situation is my mother passed away and left no will so my sister and I are awaiting probate hearings to determine the distribution of her properties. The hearings are being held up due to my grandfather who passed away a year prior to my mother's death and his will still has not been probated and until that takes place neither can my mother's. She owned two real estate properties a house in Texas and a farm in Oklahoma. The farm is titled/deeded in her name but the house in Texas is in her name but with a $60,000 mortgage against it with the est. value of the house being approx. $140,000. The mortgage is up to date and has been paid on time since her passing yet the bank, Frost bank recently stated to me and my sister that if nobody came forward and assumed the responsibility and put the mortgage in their name then they would foreclose on the property and we would lose it. My sister won't assume it, and I don't have the credit to do it myself or I would. Can Frost force the sale of the house by threats of foreclosure even though the will is still in probate and even though the loan is still being paid on schedule?
Let me add that my sister and I hate each other and since I am currently living in the house I would not put it past her to try and force me out in any way possible in efforts to try and get cash as soon as she can. We both knew the wishes of my mother as to regards to how she wanted us to distribute her estate and my sister has ignored them and become greedy and very deceitful about all of it and I want to know if she is lying to me about all of this, she is the manager of the estate and hasn't been completely honest on other matters as of yet., more