He ( ) deal with the problem without the help for his father

正确：B
can是个情态动词,没有人称和数的变化,故A是错误的.
can常与be able to互换,但can只有can/could两者形式,而be able to 则有am/is/are/was/were/will be able to等多种形式,即应该把C改为is able to,则是正确的.