On a case-by-case basis, the Public Trustee does administer a deceased's share in a HDB flat if it is of small value (≤ $50,000). You will first have to submit an online application at https://go.gov.sg/pto (Deceased's Assets other than Un-nominated CPF Monies / Baby Bonus / Edusave / PSEA) for the Public Trustee to administer the deceased's estate so that we may consider your request.