What questions did Mortimer want help answering?

Dr. Mortimer wanted to know what to do about the arrival of Sir Henry Baskerville (the heir).... should he bring to the family home? Is he in danger? Should Mortimer heed the curse when dealing with the heir?

“Then, how can I assist you?”
“By advising me as to what I should do with Sir Henry Baskerville, who arrives at Waterloo Station”—Dr. Mortimer looked at his watch—“in exactly one hour and a quarter.”

“It seems natural, does it not? And yet, consider that every Baskerville who goes there meets with an evil fate.