A single entry visa for Malaysia is only valid for up to 30 days and it cannot be extended. Neither can a Social Visit Pass.
If you want to stay in Malaysia for longer than your Pass is issued for, you have to leave the country and apply for the appropriate Malaysian Visa/Pass.
However, an extension of a Social Visit Pass may be possible in extraordinary cases, and only after consideration on a case to case basis. For example, you could receive an extension for your Social Visit Pass if you fell ill, had an accident, or if a situation in your home country (such as a war) could endanger you if you returned.
In such an event, you will have to provide evidence of your claim and show a confirmed return ticket to your home country.