Aarif writes, "My sister arrived for a visit on a tourist visa but not only she did not get a I-94, her passport merely says B2 with no date up to which she is allowed to stay. What should we do? How long can she stay? Will she have any problem during her next trip?"
The CBP has discontinued paper I94 cards, but if you still wish to have one, you can print it from here. This will also show how long she is allowed to stay. In any case, it is generally six months, unless indicated otherwise. It is not a bad idea to hang on to this print out for her next trip just for her peace of mind, though, there is no need, since the computers at the airport will have a record of her arrival and departure. The only reason she might have problem during her next trip is if she stays for a long time during this trip and then tries to come back soon because that will raise a suspicion that she does not have strong ties to her native country and may be more likely to never leave and become an illegal immigrant.