AttributeError: module 'networkx' has no attribute 'connected_component_subgraphs'

This was deprecated with version 2.1, and finally removed with version 2.4.

See these instructions

Use (G.subgraph(c) for c in connected_components(G))

Or (G.subgraph(c).copy() for c in connected_components(G))

connected_component_subgraphs has been removed from the networkx library. You can use the alternative described in the deprecation notice.

For your example, refer to the code below:

A = (B.subgraph(c) for c in nx.connected_components(B))
A = list(A)[0]