You can combine filters using a logical AND, however a filter can have at most one prefix and zero or more tags.

Did you try creating two configurations pointing to the same cloud function as so:

  <CloudFunctionConfiguration>
     <Id>1</Id>
     <Filter>
            <S3Key>
                <FilterRule>
                    <Name>suffix</Name>
                    <Value>.jpg</Value>
                </FilterRule>
            </S3Key>
     </Filter>
     <CloudFunction>arn:aws:lambda:us-west-2:444455556666:cloud-function-A</CloudFunction>
     <Event>s3:ObjectCreated:Put</Event>
  </CloudFunctionConfiguration>
  <CloudFunctionConfiguration>
     <Id>2</Id>
     <Filter>
            <S3Key>
                <FilterRule>
                    <Name>suffix</Name>
                    <Value>.png</Value>
                </FilterRule>
            </S3Key>
     </Filter>
     <CloudFunction>arn:aws:lambda:us-west-2:444455556666:cloud-function-A</CloudFunction>
     <Event>s3:ObjectCreated:Put</Event>
  </CloudFunctionConfiguration>

It doesn't seem to be possible inside a single trigger (̶w̶h̶a̶t̶ ̶a̶ ̶p̶i̶t̶y̶)̶, but still it isn't that expensive to create multiple S3 triggers for Your lambda function each with it's own suffix, most likely one of a couple of file extensions Your lamda must react to, right?