Some possible answers could be: someone from her family died, she is not getting enough sleep, she had a fight with her spouse that morning, her son is ill, she is not feeling well, etc.

A funeral would have a lot of onlookers from morning to night.

And she would be hired to wail at every funeral.

Mr Heathcliff said I might have my own way there too; only, he desired me to remember that the money for the whole affair came out of his pocket.

The sons gave him a very nice funeral, for they knew there was a fortune sitting beneath the kitchen table, and they could afford to splurge a little on the old man now.