The speaker in line 10 advises against over-focusing on personal struggles, suggesting the importance of self-awareness and balance rather than dwelling on personal misgivings.
When the speaker advises himself not to "[grope] in thine own gross darkness", he means that one should not be overly preoccupied with his or her personal misgivings or shortcomings. This phrase suggests that dwelling too much on one's own issues can lead to a kind of mental blindness or stagnation.
Considering the context provided, which emphasizes self-awareness and balance between one's abilities and actions, the correct answer to what the speaker is conveying would be B. Don't focus on your own struggles. This is aligned with the advice across the referenced texts, which emphasizes self-improvement, awareness, and the balance between introspection and external guidance.