If a bank repossess a house does the owner get any money back?

Usually the foreclose happens because the owner has the banks funds already and is refusing to repay. The bank is the one out the money, the owner has nothing to get "back".

Only if the bank can sell the house for more than the balance on the mortgage plus any expenses the bank may incur. In almost all cases, the re-sale is not enough to cover the mortgage plus costs.

If the Bank or Building Society that issued your parents their mortgage have to repossess the house due to Mortgage arrears they put the House up for Sale and are legally bound to seek the best price for it ~ in other words, not just take the first offer they get on it. If a would be buyer makes a firm offer the offer is disclosed in Newspaper adverts and asking for any further offers within a stated time period. Once the house is actually sold if the net proceeds of the sale (ie after the various selling costs are deducted) is more than the amount your parents still owed on it, then the Bank/Building Society take the amount owed to them and your parents are paid the difference. This means that their house had Positive equity in it.

However, some times a house has what is called Negative Equity. This happens when a house was bought at the peak of the market but since then property values have dropped and the house is now worth less than the outstanding mortgage on it. In these cases' the Bank/Building Society get the whole Sale price and the ex home owner owes the the difference.

So, examples of the 2 situations.
[1] Positive Equity. A house is sold with net proceeds of £200,000 from the sale. the ex Home owner owed £165,000 on their mortgage. The mortgage holder take the £165,000 owing and pays the ex owner the £35,000 difference.

[2] negative Equity. A House is sold with net proceeds from the sale being £165,000. However the ex owner owed £175,000 on their mortgage. in this case the mortgage holder takes all the £165,000 net sale proceeds and the ex owner still owes them £10,000 which they have to pay off.

So whether your parents would get anything back depends upon whether their outstanding mortgage is less than the net sale price or more than it.

If the bank sells the house for more than the outstanding mortgage, any 'surplus' will pass to the (previous) owners of the house (the bank is the owner at the time of the sale).

No.

babnk reposses the house and auctions it for whatever price anybody is willing to pay for it (so its irrelevetn how much you parents owe them or how big their morgage is)

If the house sells for more than they owe the bank, then they get the "extra"
(they owe 50k - it sells for 60k - then they get the 10k)

If it sells for less then they owe any debt left over
(they owe 60k - its sells for 50k - then they still owe 10k)

If the bank sell the house for more than:

The amount owed on the mortgage AND the banks legal fees for the foreclosure AND their costs to sell the house...

then yes, they get what's left over.

What money? They are being foreclosed on because they are not paying.

normally nope.