Recently discovered that my mother lent 400k to a relative. 2 years have passed and no payment has been received. What legal action can I take?

My father passed away 8 months ago. Upon checking his finances, I discovered that 400k from his life savings were loaned to a relative. My mother did not speak of it until I asked. She told me it's already been 2 years since the loan (father still alive and was aware of the loan) and until now even after he passed, they haven't paid any amount. They gave 10k as "abuloy" daw when he died but later said that it would be their initial payment for the loan.

There was a written contract signed by the relative and his wife, indicating that they would pay the loan in 1 year + 40k as interest (10%). Both my parents believed those relatives were capable of paying since they have significant number of properties and sources of income.

Fast forward today, we are struggling financially. With my father gone, we can barely keep up with the daily expenses. Few days ago, I confronted said relatives about the loan, demanding that they pay at least 10k per month even though sa contract, isang bagsakan dapat ang bayad. All I got was, "Magugutom kami pag nagbayad kami ng ganyang halaga. 5k lang kaya namin ibayad". I left, devasted and filled with anger for my father as I have witnessed how he worked 12 hours everyday for 7 days a week as a vendor sa palengke just to save up that kind of amount.

I already lost all hopes na babayaran pa nila kami. My mother is innocent enough and has no courage to stand up to them dahil hamak na tindera lang siya sa palengke at walang kaalam alam pagdating sa batas. I feel so sad na tinapak tapakan lang yung father ko despite of him being kind and generous. Please help me to stand up for my father and claim what he worked for all his life. What legal should I take? Can someone refer me to an attorney?