As mathepac points out, she would probably have a mortgage protection policy which would pay off the mortgage, so you would get the house without a loan attached.
You cannot inherit someone else's debts. When she dies, the executor will sell the assets and pay off the loans. If the loans exceed the assets, you will get nothing.
Assuming you get the house mortgage free, you will Inheritance Tax (formal name: Capital Acquisitions Tax) at 20% on the value above €26,000. So if the house is worth €426k, you will pay €80k.
If you live in the house for 6 years before she dies, you will be generally exempt from CAT.
Brendan