Should a mother who manages the funds of her orphans (from land revenue and a pension), and who has her own private income, separate these funds and use her private money for charities and social courtesies to avoid squandering the trust?

It is not permissible to donate an orphan's money or dispose of it except in a way that benefits them and promotes its growth, as Allah Almighty says: (And do not approach the orphan's property except in a way that is best) and (Say, "Improvement for them is best"). The guardian must preserve and invest the minor's money. The mother is not obligated to separate her money from that of her orphaned children, and it is permissible to mix with them in spending, provided that justice is observed and effort is made in estimating their expenses, so that she does not take more from their money than they need. If that happens unintentionally, there is no sin.