Nobody can give you a meaningful answer without a complete review of all of the evidence, and meeting with the District Attorney.
I am assuming your husband was convicted of Penal Code 245, assault by means likely to cause great bodily injury. The potential prison sentence is two, three or four years.
Judges use suspended sentences to emphasize a defendant may not get another chance if he screws up on probation. A suspended sentence also means an offense can never be reduced to a misdemeanor. On the plus side, if the suspended sentence is less than the maximum four years, the judge can't increase it if your husband is sent to prison.
The DA may decide not to file charges in the new case, and just proceed as a probation violation. In that case, your husband would not be entitled to a jury trial and the prosecution would only have to prove the violation was more likely than not, instead of the standard at trial, which is "beyond a reasonable doubt." Your husband also has less protection against illegal searches if the DA charges a probation violation instead of a new criminal charge.
Your husband needs an attorney to represent him, not generic advice from a stranger on the Internet. If he can't afford to hire his own lawyer, the judge will appoint one to represent him.
First, the bottom line: He needs a very good criminal defense attorney to represent him.
And now the nitty gritty: What will matter the most are the terms of his probation case. With a suspended sentence, any violation of that probation could result in the imposition of the suspended sentence. That could be up to 4 years.
Can he get a program? If this is his first drug offense, he may be eligible (on paper) for a diversion program, but if he's sentenced to prison, he won't be available to do the classes.
He'll need to sort through all this with his attorney.