If the clawback did not exist, I would suggest that the simplest, least risky approach was to pay off the mortgage. You won't earn 2.75% after tax on any deposit.
Can you explain how the clawback works? If you sell it today, how much would you have to repay? You are probably right not to sell it today. I presume that it reduces the longer you hold the property? There may be a time when it makes sense to pay it as the clawback will be relatively small.
Are you allowed to rent out the house? Is there a clawback if you do?
Keeping the €100,000 available give you great flexibility. Depending on your husband's salary, you probably would get a mortgage.
You are paying 2.75% in interest on the mortgage and can probably earn 1% net on a deposit. So this flexibility is costing you €1,750 a year. That might be ok for a year or two, but if you are happy where you are for the next 5 years, it would cost you around €10,000. Probably not worth that.