im sure guman did something to meneka

She got to know every things so she want to know more. May be after knowing she
she make kabir do all her bad things to keep
maneka alive as for her nothing is important than money.

Yes, gumaan might have mixed something in her tea and menaka is in danger. I suppose gumaan overheard kabir and menaka conversation and kalika also informed her of the happenings in desai home. But kabir will not obey gumaan at any cost. I guess samud may visit menaka to know facts and save her which may finally lead to London plot.