The correct answer is: Only assumption I is implicit.
The statement “I cannot contact you on phone from Karshik” does not provide enough information to support the assumption that “Nowadays it is difficult to contact on phone.” It is possible that the speaker cannot contact the listener on phone from Karshik because there is no telephone facility available in Karshik, or because the listener’s phone is not working, or because the speaker does not have the listener’s phone number. The statement does not provide any information about the difficulty of contacting people on phone in general.
Assumption I is implicit in the statement because if there is no telephone facility available in Karshik, then the speaker cannot contact the listener on phone from Karshik. Assumption II is not implicit in the statement because the statement does not provide any information about the difficulty of contacting people on phone in general.