Karen's thoughts seem disjointed and illogical, and she suffers from frequent hallucinations. in addition, the syntax of her speech is unusual. karen is most likely to be suffering from:

The symptoms descibed indicate that Karen is most likely to have schizophrenia. 

Schizophrenia is a mental disorder which is characterized by the lack of understanding reality. There are no specific parameters to have a precise diagnose - the symptoms are various and different from person to person - but there are common factors, as the ones listed above in Karen's case, and others include anxiety, lack of motivation, false beliefs, depression, and abnormal social behaviours. 

Della is not the wealthiest person. she has to beg people for money which means she probably doesn't have a job.