Donald purposely did not tell Matilda they were coming, hoping to effect a reconciliation between her and Scrooge, but Matilda refuses to believe Scrooge is sincere and thinks he is only interested in the treasure.
In an effort to repair Matilda's bond with Scrooge, Donald chose not to inform her about their visit, hoping to persuade her that Scrooge's actions were motivated by a desire for reconciliation rather than personal gain. However, Matilda remains skeptical and believes Scrooge is only interested in the treasure.